Comparative list R20 - R27
The following table is listing several components (currently 127 covered) of the BMW single cylinder models from R20 to R27, providing criteria that should allow to associate any of the components to the right model with the least possible effort (a close inspection, a folding rule and a small engineers square should suffice).
Display table configuration and comments
General notes:
  • Disclaimer: All values listed in this table have been put together with the utmost care from several different sources (documents, technical sketches, measurements, forum). But, as a final verification of these values is beyond our possibilites, their correctness cannot be guarantied.
  • Please send all change requests, corrections and additions solely via the forum of the BMW Einzylinder-Zentrum (there's an English language forum section available).
  • Generally BMW sometimes introduced improved parts before the new model had been officially released (e.g. R25/3 aluminium kickstarts on R25/2 machines) or cleared the previous model's stock before actually using the originally designed components for the new one (e.g. the R25/3 head light housings and Eber tail lights to be found on early R26s as well or the first R25/2s being equipped with the 24 mm intake R25-cylinder-heads, before BMW changed to 22 mm intake).
  • The table contains some modifications BMW did introduce even during the production time of specific models...and if BMW considered these improvements substantial enough it was sometimes recommended to apply them even to older machines of the same type (e.g. the black cylinder head on the r25/2s or the taper roller bearings for the R25/3 wheel hubs).
  • The language, in which the table is displayed at start-up, relies on any of the following options: browser page preferences, direct links to any of the components or via parameter at the end of the link address (?DE or ?EN).
  • A rather unostentatious page providing all large graphics for copying and printing purposes may be found >here<.
Instructions for use and explanations:
  • The dropdown list allows to directly jump to any component, order and numbering are aligned with the structure of the original 7-digit spare parts lists, giving the main group for orientation.
  • The list on the right side is equivalent, but historically originated, and therefore grouped differently, each component name is a link to the corresponding description.
  • It should be common sense that the links of either list will only work if the intended component has not been hidden - see configuration section below.
  • A small number of items is best understood in context (like the clutch lever adjusting screw) or not exactly BMW specific (like the tail light bulbs), these will not be listed as independent components, but only attached to the respective "mother" components (marked with a +) and in the aforementioned dropdown list.
  • In case a component has been changed significantly during the production period of a model, the respective frame number will be shown in bold and italic style. The arrow in front of the number does indicate, up to which frame number the properties listed are valid, if the arrow is following the number, then the properties given are valid from that frame number onwards (e.g. 234 432 = properties are valid from no. 234 432 onwards).
  • For some measurements there are sketches available at the appropriate place in the table that will explain where exactly the measurements have been taken-by hovering the mouse over the thumbnails the sketches will be enlarged to max. VGA (640x480) size.
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Meaning of the pictograms:
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    -if required- the sketch on the page with the larger images is displayed with a higher resolution and more details (no link!).
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    -if required- there is a connection to or a strong dependence on another component not listed directly next to this one (link!).
  • Within the table:
    -if required- here's a value still missing. In case you feel able to help out, plase feel free to contribute.
    -if required- value not required due to strong technical differences or other, easier to be measured criteria.
    / -if required- "nearside" or "offside" (to describe side-specific differences).
Configuration:
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Components:
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basic information, frame
fork, suspension springs front, yokes, head light holder, adjusting nut steering bearing, thumb screw+, resistance plate, mudguard front wheel, brake holder
head light housing, head light, speedometer, speedo cable, connector plate, ignition key, horn
handlebars mounting, risers, handlebars, handlebars switches, throttle cable
seat carrier, seat spring(s), battery carrier, center stand, stud lower engine mounting, screw upper engine mounting, footpegs rider, footpegs pillion, bumper kick start lever
mudguard rear wheel, tail light+
tank+, fuel tap, air intake filter, carburettor+, slide top nut, carburettor slide, exhaust pipe, exhaust pipe support, silencer
crankcase, cylinder, cylinder head, rocker covers, oil sump, bearing plate, generator cover
crankshaft, sprocket wheel, oil slinger plate, piston rod, piston, disc flywheel, clutch spring(s), pressure plate, clutch plate, pressure ring
camshaft, breather, oil pump, oil dipstick
tappets, push rods, rocker shafts, rocker arms, valves, valve-guides, valve springs, valve collets and retainers
generator+, ignition timing adjustment
gear box general, transmission housing cover, shifting mechanism, kick starter shaft, primary shaft, thrust rod, spacer+, clutch release lever+, foot shift lever, kick start lever, flexible disc flanges
flexible disc, cover ring, cardan drive, u-joint protecting bell, gear and crown wheel, rear axle gearbox, cover rear axle gearbox, rear axle holder, axle clamping bolt, slide bush
spring cover top, spring cover bottom, grease cap (bottom), suspension springs rear, plunger post
front axle, rear axle, wheels, spokes, hub, wheel bearing bush, spacer tubes, wheel bearings, pressure bushings, wheel bearings fixation, hub caps, brakes general
brake cam front, brake lever front wheel, adjustment screw
brake pedal, brake rod, brake cam rear, brake lever rear wheel
Models:
R20    R23 R24 R25(/1)    R25/2    R25/3 R26    R27 R50 (Zylinder)
Basic information
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Internal designation frame 220/1 223/1 224/1 225/1 225/2 225/3 226/1 226/2
Years of manufacture 1937-1938 1938-1940 1948-1950 1950-1951 1951-1953 1953-1956 1956-1960 1960-1966
Frame numbers 100 001 - 105 004 106 001 - 114 203 200 001 - 212 007 220 001 - 243 400 245 001 - 283 650 284 001 - 331 705 340 001 - 370 242 372 001 - 387 364
Total manufactured 5,000 8,200 12,020 23,400 38,651 47,700 30,236 15,364
Frame number <-> engine number usually non-matching numbers usually non-matching numbers matching numbers matching numbers matching numbers matching numbers matching numbers matching numbers
Production year-VIN 1937: 100 001-103 153
1938: 103 154-105 004 		1938:106 001-108 000
1939: 108 001-114 011
1940:114 012-114 203 		... ... ... ... ... ...
Frame
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Frame number location on right lower frame end
behind the brake lever 		on right lower frame end
behind the brake lever 		at the right engine mounting cube at the right engine mounting cube
220 061 on right upper
rear wheel suspension support 		on right upper rear wheel
suspension support 		on the steering head's right side on the steering head's right side on the steering head's right side
Rear wheel suspension rigid rigid rigid Pushrod suspension Pushrod suspension Pushrod suspension long swingarm long swingarm
Assembly method bolted bolted bolted welded welded welded welded welded
Suitability for sidecar not suitable for sidecar not suitable for sidecar not suitable for sidecar sidecar mounts welded to frame sidecar mounts welded to frame,
first series has lower right mount bolted 		sidecar mounts welded to frame sidecar mounts welded to frame
344 637 subframe required 		subframe required
Mounting point for silencer
lower left corner of frame 		bolt hole at axle eye bolt hole at axle eye bolt hole at axle eye clamping bolt
plunger post support 		clamping bolt
plunger post support 		dual-tapered bushing, part of
plunger post support 		dual-tapered bushing
outside the frame 		silent-block bushing
outside the frame
Fork
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27 R50
System telescopic fork telescopic fork telescopic fork telescopic fork telescopic fork telescopic fork Earles fork Earles fork Earles fork
Steering lock right side, bottom yoke right side, bottom yoke right side, bottom yoke top yoke top yoke headstock, bottom left side headstock, bottom left side headstock, bottom left side headstock, middle left side
Rubber bellows yes yes yes yes yes no no no no
Right fork end left-hand thread for axle left-hand thread for axle left-hand thread for axle left-hand thread for axle
227 407 plain drill for axle 		plain drill for axle plain drill for axle plain drill for axle plain drill for axle
Ear for hydraulic steering damper no no no no no no no yes
Suspension springs front
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Length relaxed (± 2 mm) 250 mm 250 mm 250 mm 282 mm 282 mm 372 mm 286 mm 286 mm
Wire diameter 4,3 mm 4,3 mm 4,3 mm 4.4 mm 4.4 mm 4.4 mm 5.8 mm 5.8 mm
Spring outer diameter 27.1 mm 27.1 mm 27.1 mm 27 mm 27 mm 27.2 mm 47.6 mm 47.6 mm
Number of coils 35 35 35 39 both ends progressive 39 both ends progressive 51 both ends progressive 24 both ends progressive 24 both ends progressive
Yokes
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Mounting points for risers holes in the middle of the yoke arms holes in the middle of the yoke arms holes in the middle of the yoke arms holes, "jutting out" to the back holes, "jutting out" to the back cones in the middle of the yoke arms cones, "jutting out" to the front holes in the middle of the yoke arms
Bottom yoke two holes for bolting on bracket two holes for bolting on bracket two holes for bolting on bracket Two eyes for cables, one per arm (centered) Two eyes for cables, one per arm (centered) M8 thread for horn mount centered at front >doesn't exist< >doesn't exist<
Steering lock eye at bottom yoke's right side eye at bottom yoke's right side eye at bottom yoke's right side insertion hole at top yoke's left side insertion hole at top yoke's left side vertical slot on steer tube's left side vertical slot on steer tube's left side vertical slot on steer tube's left side
Head light holder
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design
(all with arm to front for headlight) 		cone, height 160 mm
bottom Ø50 mm,
top Ø 44 mm with "collar" 		cone, height 160 mm
bottom Ø50 mm,
top Ø 44 mm with "collar" 		cone, height 160 mm
bottom Ø50 mm,
top Ø 40 mm with "collar" 		cylinder, height 150 mm, Ø 50 mm cylinder,
height 150 mm, Ø 50 mm 		cylinder,
height 150 mm, Ø 50 mm 		half cylinder shell,
height 105 mm, 37 mm wide 		half cylinder shell,
height 105 mm, 37 mm wide
Made from 1 piece, rolled and welded 1 piece, rolled and welded 2 pieces, welded 1 piece, rolled and welded 1 piece, rolled and welded 2 pieces, welded 2 pieces, welded 2 pieces, welded
Special features tube part tube overlaps 6mm
on the inner side 		tube overlaps 40 mm
beneath holding arm 		tube overlaps 40 mm
beneath holding arm 		tube seamless >doesn't exist< >doesn't exist<
Adjusting nut steering bearing
dimensioned sketch
all: bearing seat Ø 34 mm
thread M28x1.5
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Total height (value A) 14 mm 14 mm 14 mm 14 mm 14 mm 16 mm 16 mm 16 mm
Height top segment (value B) 3 mm 3 mm 3.5 mm 3.5 mm 3.5 mm 6.5 mm 6.5 mm 6.5 mm
Design Top side plain (like 1) Top side plain (like 1) Top side plain (like 1) Top side plain (like 1) Top side plain (like 1) Top side 2 opposite notches
no thread there (like 2) 		Top side 2 opposite notches
no thread there (like 2) 		Top side 2 opposite notches
no thread there (like 2)
Thumb screw
Springs 0.8 x 5 x 12 DIN 2098
Steel balls diameter 5.5 mm
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Handle (collar height A) two wings two wings two wings two wings two wings two wings star-shaped (3 mm) star-shaped (3 mm, later 15 mm)
Rod length 200 mm 200 mm 224 mm 224 mm 224 mm 224 mm 246 mm 246 mm
thread
(hole for split pin 2 mm from lower end) 		M8, 35 mm long M8, 35 mm long M8, 35 mm long M8, 35 mm long M8, 35 mm long M8, 35 mm long M8x1, 35 mm long M8x1, 35 mm long
Height lock plate cover 10 mm 10 mm 22 mm 22 mm 22 mm 22 mm 19 mm 19 mm
Resistance plate
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
centre distance (value A) 100 mm 100 mm 95 mm 75 mm 75 mm 75 mm 75 mm 75 mm
Diameter hole for
retaining screw (value B) 		6.5 mm 6.5 mm 6.5 mm 14.5 mm 14.5 mm 14.5 mm 16.1 mm 16.1 mm
Special feature (criterion C) >doesn't exist< >doesn't exist< latch for horn latch, 25 mm wide latch, 25 mm wide latch, 25 mm wide hole, diameter 19.8 mm hole, diameter 19.8 mm
Mudguard front wheel
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Stays assemblyfront
middle
back
 inside, riveted
>doesn't exist<
inside, riveted 		inside, riveted
>doesn't exist<
inside, riveted 		inside, riveted
>doesn't exist<
inside, riveted 		inside, riveted
outside, riveted
inside, riveted 		outside, bolted
outside, riveted
inside, riveted 		outside, bolted
outside, riveted
inside, riveted 		outside, bolted
>doesn't exist<
No stays, mounted
directly to the rocker 		outside, bolted
>doesn't exist<
No stays, mounted
directly to the rocker
Visible mudguard width (value A)
measure behind fork,
or behind middle stay 		22+0.5 cm 22+0.5 cm 25.4+0.5 cm 25.4+0.5 cm 22+0.5 cm 22+0.5 cm 22+0.5 cm
Length of lower stay
from inner flange mudguard
to 's end (value B) 		24 cm 24 cm 22.5 cm >doesn't exist< >doesn't exist<
Length inner reinforcement (value C) 78 mm 78 mm 132 mm >doesn't exist< >doesn't exist<
Brake holder
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
System half-width brake half-width brake half-width brake half-width brake half-width brake full-width brake full-width brake full-width brake
Cable ends at brake lever brake lever brake lever brake lever brake lever brake holder brake holder brake holder
Visible length brake holder stud 25 mm 25 mm 23 mm 23 mm 28 mm 28 mm 28 mm
Position of drain hole
(torque bracket horizontal) 		>doesn't exist< >doesn't exist< >doesn't exist< "7 o'clock" "7 o'clock" "7 o'clock" "6 o'clock" "6 o'clock"
Head light housing
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Ø front opening (value A)
(depending on manufacturer) 		164+1 mm (Bosch) 164+1 mm (Bosch) 170+1 mm (Bosch) 170+1 mm (Bosch)
175+1 mm (Notek) 		170+1 mm (Bosch) 170+1 mm (Bosch) 170+1 mm (Bosch) 170+1 mm (Bosch)
Length (value B)
(depending on manufacturer) 		(Bosch) (Bosch) (Bosch) 190 mm (Bosch)
(Notek) 		190 mm (Bosch) 190 mm (Bosch) 190 mm (Bosch) 190 mm (Bosch)
Alongside ignition switch charge control
fuse 		charge control
fuse 		charge control >nothing< >nothing< >nothing< >nothing< >nothing<
Above speedometer >nothing< >nothing< >nothing< charge control
fuse 		charge control
fuse 		>nothing< >nothing< >nothing<
Below speedometer >nothing< >nothing< >nothing< >nothing< neutral indicator heart-shaped charge control
and neutral indicator 		heart-shaped charge control
and neutral indicator 		heart-shaped charge control
and neutral indicator
Horn dent no no no no no yes early machines like R25/3
then without 		no
Head light
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Manufacturer and model Bosch EAS 150 2 T 45 Bosch EAS 150 2 T 145 P Bosch LE/MTA 160x2 (4/1) Bosch LE/MTA 160x2 (4/1)
Notek 		Bosch LE/MTA 160x2 Bosch LE/MTA 160x2 Bosch LE/MTA 160x2 Bosch LE/MTA 160x2/48
Speedometer
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
W= (valid for km/h!) 1,0 solo
 1,0 solo
 1,0 solo
 1,05 solo
1,2 side car 		1,05 solo
1,2 side car 		1,0 solo
1,15 side car 		1,0 solo
1,25 side car 		1,0 solo until no. 379 494
1,08 solo from no. 379 495
1,25 side car
Display range 0-120 km/h 0-120 km/h 0-120 km/h 0-120 km/h 0-120 km/h 0-140 km/h solo
0-120 km/h side-car 		20-140 km/h
possibly 0-140 km/h, too 		20-140 km/h solo
10-110 km/h side-car
Shifting marks 25-50 25-50 20-35-60 20-35-60 25-45-70 25-50-75 solo
20-40-65 side-car 		25-55-80 solo 25-55-80 solo W=1,0
35-60-90 solo W=1,08
20-45-65 side-car
Speedo cable
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Cable total length(value A) 110 cm 110 cm 115.5 cm 115.5 cm 115.5 cm 115.5 cm 119 cm 119 cm
Housing total length (value B) 108 cm 108 cm 112.5 cm 112.5 cm 112.5 cm 112.5 cm 116 cm 116 cm
Housing outer diameter (value C) 8 mm 8 mm 8 mm 8 mm 8 mm 8 mm 7 mm 7 mm
Ferrule speedo side length(value D) 36 mm 36 mm 27 mm 27 mm 27 mm 27 mm 27 mm 27 mm
Socket gearbox side length(value E) 32 mm 32 mm 30 mm 30 mm 30 mm 30 mm 35 mm 35 mm
Socket gearbox side diameter (value F) 16 mm 16 mm 16 mm 16 mm 16 mm 16 mm 11.5 mm 11.5 mm
Union nut speedo (feature G) M18x1.5 M18x1.5 M18x1.5 M18x1.5 M18x1.5 M18x1.5 M18x1.5 M18x1.5
Protruding length speedo side (value H)
Driver gearbox (feature I) like 1 (2.5 mm x 8 mm) like 1 (2.5 mm x 8 mm) like 2 (2.7 mm x 2.7 mm) like 2 (2.7 mm x 2.7 mm) like 2 (2.7 mm x 2.7 mm) like 2 (2.7 mm x 2.7 mm) like 2 (2.7 mm x 2.7 mm) like 2 (2.7 mm x 2.7 mm)
Connector plate
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Difference
Ignition key
Rolf's ignition key guide (German)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Number of catches towards iginition switch 2 low 2 low 2 low 2 low 2 low 1 high, rear side 1 high, rear side 1 high, rear side
Horn
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Manufacturer and model Bosch FD 6 D S 10 Bosch FC 6 1 black Bosch FCE 6/1,
green Bosch FCE 6/6 		black Bosch FCE 6/1,
later HO/FCF 6/1
green Bosch FCE 6/6 		Bosch FCE 6/1 resp. HO/FCF 6/8
or NORIS HE6 		Bosch HO/FCF 6/8 or
NORIS HE6 		Bosch HO/FCF 6 A1 or
HO/FCF 6 A 20 		HO/FCH 6/1
Location on bike left side of gearbox left side of gearbox below the tank
to resistance plate 		below the tank
to frame 		below the tank
to frame 		below the headlight
to fork bottom yoke 		below the tank
to frame 		below the tank
to frame
Handlebars mounting
schematic sketch
without washers and nuts
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Parts from top none (bolted on directly) none (bolted on directly) 1. steel cover
2. rubber washer
3. rubber tube
4. rubber washer
5. steel cover 		1. steel cover
2. rubber washer
3. rubber tube
4. rubber washer
5. steel cover 		1. steel cover
2. rubber washer
3. rubber tube
4. rubber washer
5. steel cover 		1. rubber cone
2, steel spacer stube
3. rubber cone
4. washer 		1. rubber cone
2, steel spacer stube
3. rubber cone
4. washer 		1. metal washer spacer
Dimensions main rubber part
height (value A) x inner diameter
(value B) x outer diameter (value C) 		>doesn't exist< >doesn't exist< 12 mm x Ø 13 mm x Ø 29 mm 12 mm x Ø 13 mm x Ø 29 mm >doesn't exist<
Risers
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Clamp handlebars half t-head bolt M8x30
from above, handle bar backside 		half t-head bolt M8x30
from above, handle bar backside 		half t-head bolt M8x30
from above, handle bar backside 		hex-head bolt M8x1x22
from the rear, handle bar backside 		hex-head bolt M8x1x22
from the rear, handle bar backside 		half t-head bolt M8x1x74
from above, handle bar frontside 		half t-head bolt M8x1x74
from above, handle bar frontside 		half t-head bolt M8x1x62
from above, handle bar backside
Mounted to top yoke via integral bolt
(hex nut M10x1) 		integral bolt
(castle nut M10x1) 		integral bolt
(castle nut M10x1,
later M8x1x22 bolt) 		integral bolt M10x1x35
(castle nut M10x1) 		integral bolt M10x1x35
(castle nut M10x1) 		handle bar clamping bolt
(castle nut M8x1) 		handle bar clamping bolt
(castle nut M8x1) 		handle bar clamping bolt
(castle nut M8x1)
Orientation risers handlebars as far to
the back as possible 		handlebars as far to
the back as possible 		handlebars as far to
the back as possible 		handlebars as far to
the back as possible 		handlebars as far to
the back as possible 		handlebars as far to
the back as possible 		handlebars as far to
the back as possible 		handlebars as far to
the front as possible
Handlebars
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Width 73 cm 73 cm 75 cm 72 cm 70 cm
Magura 69 cm 		66 cm solo
69 cm side car 		66 cm solo
69 cm side car
Handlebars switches
TOS = toggle-type switch,
SWS = swivel-style switch
dimmer switch not further specified is electrical
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Left hand side mechanical dimmer switch (TOS)
and horn 		mechanical dimmer switch (TOS)
and horn 		mechanical dimmer switch (TOS)
and horn 		mechanical dimmer switch (TOS)
and horn 		dimmer switch (TOS)
and horn switch, chrome housing 		dimmer switch (TOS)
and horn switch, chrome housing 		dimmer switch (TOS)
and horn switch, chrome housing 		dimmer switch (TOS)
and horn switch, chrome housing
379 498 dimmer switch (TOS),
horn, flasher, chrome housing
385 265 dimmer switch (SWS),
flasher, support tilted to left
Number of strands 4 4 4 4
379 498 5
385 265 4
Right hand side alternative position for
dimmer switch and horn
requ. different head light housing 		alternative position for
dimmer switch and horn
requ. different head light housing 		>nothing< >nothing< >nothing< >nothing< >nothing< Indicator switch (TOS)
and flasher, chrome housing
379 498 indicator (SWS),
support horizontal
385 265 indicator (SWS),
horn, support tilted to right
Number of strands >if required< >if required< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 5
379 498 3
385 265 4
Throttle cable
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Cable diameter x
total length incl. terminals 		Ø 1.5 mm x 900 mm Ø 1.5 mm x 910 mm Ø 1.5 mm x 850 mm Ø 1.5 mm x 875 mm
Total length outer cable incl. ferrules 810 mm 790 mm 740 mm 780 mm
Terminal handlebars side form
section I diameter x length 		barrel (like 1)
Ø 2.5 mm x 5.5 mm 		barrel (like 1)
Ø 2.5 mm x 5.5 mm 		barrel (like 1)
Ø 2.5 mm x 5.5 mm 		barrel (like 1)
Ø 2.5 mm x 5.5 mm
Terminal carburettor side form
section I diameter x length 		barrel (like 1)
Ø 2.5 mm x 5.5 mm 		barrel (like 1)
Ø 2.5 mm x 5.5 mm 		barrel (like 1)
Ø 2.5 mm x 5.5 mm 		barrel (like 1)
Ø 2.5 mm x 5.5 mm
Note for mixing chamber cover
without throttle cable elbow 		for mixing chamber cover
without throttle cable elbow 		for mixing chamber cover
without throttle cable elbow 		for mixing chamber cover
with throttle cable elbow 		for mixing chamber cover
with throttle cable elbow 		for mixing chamber cover
with throttle cable elbow
Seat carrier
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Seat top Drilastic Drilastic Drilastic Pagusa Pagusa Pagusa Pagusa Pagusa
Spring(s) bolted below rear bolts below rear bolts below rear bolts below rear bolts to vertical spring lever to vertical spring lever to vertical spring lever to vertical spring lever
adjustable range to
rider's weight (positions) 		no no no 2 spring mounting pos. 60-100 kg (4 pos.) 60-100 kg (4 pos.) 60-100 kg (4 pos.) 60-100 kg (4 pos.)
Holes for seat bearing Ø 8 mm Ø 8 mm Ø 8 mm Ø 8 mm Ø 8 mm Ø 10 mm Ø 10 mm Ø 10 mm
Seat spring(s)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Saddle spring(s) two upright (black) two upright (black) two upright one upright one horizontal one horizontal one horizontal one horizontal
Lower eyelet ... vertical vertical vertical horizontal not applicable not applicable not applicable not applicable
Spring type
(all coils springs) 		compression spring compression spring compression spring compression spring extension spring extension spring extension spring extension spring
Battery carrier
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Tension strap steel, one part steel, one part steel, two parts
also rubber 		steel, two parts steel, two parts
263 051 rubber 		rubber strap rubber strap rubber strap
Center stand
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Springs One tension spring side pull
flat retaining spring 		One tension spring side pull
flat retaining spring 		One tension spring side pull
flat retaining spring 		One tension spring side pull
flat retaining spring 		One tension spring side pull
267 301 center spring 		Two tension springs center Two tension springs center Two tension springs center
Distance bore centre
to "face" (value A) 		ca. 15 mm ca. 15 mm ca. 15 mm ca. 20 mm ca. 15 mm ca. 40 mm ca. 15 mm ca. 15 mm
Distance "face"
to ground (value B) 		ca. 190 mm ca. 190 mm ca. 190 mm ca. 210 mm ca. 225 mm ca. 230 mm ca. 255 mm ca. 255 mm
U-shaped arm for spring yes yes yes no no no no no
Stud lower engine mounting
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Length (value A) 265 mm 265 mm 265 mm 265 mm 265 mm 257 mm 257 mm completely different solution
Diameter shank (Value B) 12 mm 12 mm 12 mm 12 mm 12 mm 12 mm 12 mm completely different solution
Both threads diameter x length
(criterion C) 		M12x1.5 x 20 mm M12x1.5 x 20 mm M12x1.5 x 20 mm M12x1.5 x 20 mm M12x1.5 x 20 mm M12x1.5 x 20 mm M12x1.5 x 20 mm completely different solution
Screw upper engine mounting
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Length (value A) 195 mm 195 mm 200 mm 200 mm 200 mm 250 mm 250 mm completely different solution
Diameter shank (Value B) 10 mm 10 mm 10 mm 10 mm 10 mm 10 mm 10 mm completely different solution
Thread diameter x length (criterion C) M10x1 x 15 mm M10x1 x 15 mm M10x1 x 15 mm M10x1 x 15 mm M10x1 x 15 mm M10x1 x 15 mm M10x1 x 15 mm completely different solution
Footpegs rider
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design tube tube tube L-shaped L-shaped L-shaped L-shaped L-shaped
Hirth serrations (criterion A) >doesn't exist< >doesn't exist< >doesn't exist< coarse (15 teeth) coarse (15 teeth) coarse (15 teeth) coarse (15 teeth) coarse (15 teeth)
Centre distance (value B) not applicable not applicable not applicable 50 mm 50 mm 50 mm 50 mm 50 mm
Cross-section in rubber round round round hexagonal hexagonal hexagonal hexagonal hexagonal
Footpegs pillion
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design rear
(only non-hinged variety!) 		L-shaped L-shaped L-shaped L-shaped L-shape L-shaped L-shaped L-shaped
Hirth serrations (criterion A) coarse (15 teeth) coarse (15 teeth) coarse (15 teeth) coarse (15 teeth) coarse (15 teeth)
Centre distance (value B) 50 mm 50 mm 50 mm 110 mm 110 mm
Cross-section in rubber hexagonal hexagonal hexagonal hexagonal hexagonal
Bumper kick start lever
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Attached via bolt-on mount bolt-on mount bolt-on mount bolt-on mount bolt-on mount bolt-on mount bolt-on mount mount welded to frame
rubber part specific rubber part specific rubber part specific rubber part specific rubber part specific rubber part specific rubber part specific rubber part main stand bumber rubber
thickness of rubber above
the frame tube (value A) 		16 mm 16 mm 16 mm 16 mm 16 mm 26 mm 16 mm
Mudguard rear wheel
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Cable duct no no no no yes yes yes yes
Passing drive shaft cut out cut out and
cover plate screwed in place 		wide waist wide waist
Length of upright stay
from inner flange mudguard
to stay's end (value A) 		>doesn't exist< >doesn't exist< 24 cm 18 cm 18 cm 14 cm >doesn't exist<
attached to suspension cover 		>doesn't exist<
attached to suspension cover
Rear mounting of
luggage carrier 		two rivets two rivets one screw one screw two screws M6 two screws M6 two screws M6 two screws M6
Hinge
(knuckles mudguard + flip end) 		no no no yes
(3 + 2) 		yes
(3 + 2) 		yes
(2 + 1) 		yes
(2 + 1) 		yes
(2 + 1)
End of rear stay closed eye closed eye closed eye stud bolt M8 stud bolt M8 stud bolt M8 eye,
hook-like opened 		hole or forked
Holes for tail light
mounting screws 		3 (2 top, 1 bottom)
from 09/1958 4 (2 top, 2 bottom) 		4 (2 top, 2 bottom)
Tail light
Rolf's tail light history (German)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design Bosch "egg-shaped"
type JN 7 K 1 		Bosch "egg-shaped"
type JN 7 K 1 		Noris tail light Eber tail light Eber tail light Eber tail light Eber tail light "3 bolts"
from 09/1958 Hella "ton"
(cylindrical) 		Hella "ton" (conical)
cable comes from extern extern extern extern through mudguard through mudguard through mudguard through mudguard
mounting screws 3 (2 top, 1 bottom) 4 (2 top, 2 bottom)
Tail light lens semicircle, Ø ca. 27 mm semicircle, Ø ca. 27 mm round, Ø ca. 25 mm round, Ø 47 mm round, Ø 47 mm (1951)
round, Ø 51 mm (from 1952) 		round, Ø 51 mm and
stop light above 		round, Ø 51 mm, very thick
ton Ø 95 mm 		round, Ø 95 mm
Glas holder >doesn't exist< >doesn't exist< Aluminium ring Aluminium ring Aluminium ring Aluminium ring Coated steel ring with
chromed ring slid on 		Coated steel ring
Bulbs bulb 3W
tail light 		bulb 3W
tail light 		bulb 2W
tail light 		15 mm bulb 3W
tail light 		Sofitt bulb
tail light 5W 		2 Sofitt bulbs
tail 5W and stop light 10W 		Eber Bilux-bulb 5/21W
"ton" has Bilux-bulb 5/21W
tail and stop light
bulb 5W license plate 		Bilux-bulb 5/21W
tail and stop light
bulb 5W license plate
Tank
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Tool compartment on top "on top"
 on top integrated
hinges on the right side 		on top integrated
hinges on the right side 		on top integrated
hinges on the right side 		on top integrated
hinges at the bottom 		left side integrated
hinges at the bottom 		on top integrated
hinges at the bottom 		on top integrated
hinges at the bottom
Front mounting "high" brackets "high" brackets "high" brackets "high" brackets "high" brackets "low" brackets (old version)
"high" brackets (new) 		bushing in the beading bushing in the beading
Rear mounting
All threads M8x1! 		brackets brackets brackets brackets closed insert nut L-bracket with thread (old)M8
closed insert nut (new) 		closed insert nut closed insert nut
Fuel tap mounted on right side right side right side right side right side left side left side left side
Connexion thread for fuel tap inside thread M14x1.5 inside thread M14x1.5 inside thread M14x1.5 outside thread M16x1 outside thread M16x1 outside thread M20x1 outside thread M20x1 outside thread M20x1
Equaliser hose no no no no no yes yes yes
Intake tube no no no no no yes no no
Screws for BMW badge half round head screw
M4x8 		half round head screw
M4x8 		lens head countersunk screw
M3x10 		lens head countersunk screw
M3x6 		lens head countersunk screw
M4x8 		lens head countersunk screw
M4x8 		lens head countersunk screw
M4x8 		lens head countersunk screw
M4x8
Fuel tap
flow rate min. 250 ml/min
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Type "Frankfurter Modell" "Frankfurter Modell" "Frankfurter Modell" Everbest FLR 1140FF Everbest FLR 1140FF Everbest "Torpedo" Everbest "Torpedo" Everbest "Torpedo"
Tank side connexion thread inside thread M14x1.5 inside thread M14x1.5 inside thread M14x1.5 outside thread M16x1 outside thread M16x1 outside thread M20x1 outside thread M20x1 outside thread M20x1
Air intake filter
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
System Metal mesh filter Metal mesh filter Metal mesh filter Metal mesh filter Metal mesh filter Metal mesh filter Metal mesh cartridge Metal mesh cartridge
paper cartridge from
no. 379 582
Exit diameter 35 mm 35 mm 35 mm 35 mm 35 mm 40 mm 40 mm 40 mm
Diameter housing 95 mm 95 mm 100 mm 100 mm 95 mm 95 mm 120 mm 120 mm (metal mesh)
106.5 mm (paper cartridge)
Mounting position straight to carburettor straight to carburettor straight to carburettor straight to carburettor straight to carburettor tank front right bottom
to the "snorkel" 		in air filter box in air filter box
Carburettor
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Type AMAL Typ M74-428S AMAL Typ M74-435S Bing Type AJ 1/22/27 Bing Type 1/22/28 Bing Type 1/22/44
or SAWE Typ K 22 F 		Bing Type 1/24/41
1/24/42 from Oct. 1953
or SAWE K 24 F 		Bing Type 1/26/46
then 1/26/52
1/26/55 from Jun. 1956 		Bing Type 1/26/68
1/26/79 from Jan 1962 ...
... to no. 379 581
1/26/83 from no. 379 582
1/26/93 from no. 384 365
Float gauge weight 7 gr 7.5 gr 11 gr 11 gr Bing 11 gr
SAWE 8 gr 		Bing 11 gr
SAWE 8 gr 		Bing 1/26/46 = 11 gr
Bing 1/26/52 = 11 gr
Bing 1/26/55 = 7 gr 		Bing 1/26/68 = 7 gr
Bing 1/26/79 = 11 gr
Bing 1/26/83 =11 gr
Bing 1/26/93 = 11 gr
Potential replacements
not authentic, but functional
Gero's carburettor list (German) 		... AMAL 22E1B ... ... ... Mikuni VM24-473 Bing 1/26/111,
Bing 1/26/113,
Bing 1/26/123,
Mikuni VM26-665,
AMAL 27/376 		Bing 1/26/111,
Bing 1/26/113,
Bing 1/26/123,
Mikuni VM26-665,
AMAL 27/376
Slide top nut
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Outer diameter (value A) 36 mm 36 mm 37 mm 39 mm Bing 39 mm
SAWE 		Bing 39 mm
SAWE 37 mm 		41 mm 41 mm
Thread M30x1 M30x1 M32x1 M34x1 Bing M34x1
SAWE 		Bing M34x1
SAWE 		M38x1 M38x1
rim detail like 1 like 1 like 1 like 1 Bing like 1
SAWE like 3 		Bing like 1
SAWE like 3 		like 2 like 2
Carburettor slide
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Part number manufacturer AMAL 4/052 AMAL 4/052 Bing 22-360 Bing 22-460 Bing 22-460
SAWE 023 		Bing 22-470
SAWE 151 		Bing 22-540 Bing 22-540
diameter x length Ø 25.4 mm x 28.6 mm Ø 25.4 mm x 28.6 mm Ø 24.5 mm x 38.4 mm Ø 26.95 mm x 39.8 mm Bing Ø 26.95 mm x 39.8 mm Bing Ø 26.95 mm x 41.8 mm
SAWE Ø 27,95 mm x 35 mm 		Ø 29.45 mm x 42 mm Ø 29.45 mm x 42 mm
Guide
from above (trough top nut),
12 o'clock=flange, 6 o'clock=intake 		slots at 3 and 9 o'clock slots at 3 and 9 o'clock "nose" at 9 o'clock "nose" at 6 o'clock Bing "nose" at 6 o'clock Bing "nose" at 6 o'clock
SAWE groove at 6 o'clock 		"nose" at 9 o'clock "nose" at 9 o'clock
Exhaust pipe
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
manifold outer diameter (value A) 36 mm 36 mm 36 mm 36 mm 36 mm 30 mm 36 mm 36 mm
Pipe orientation at cylinderhead
as seen from above (criterion B) 		aligned to
bike's centre line (like 1) 		aligned to
bike's centre line (like 1) 		aligned to
bike's centre line (like 1) 		aligned to
bike's centre line (like 1) 		aligned to
bike's centre line (like 1) 		aligned to
bike's centre line (like 1) 		misaligned by 10 ° to
bike's centre line (like 2) 		misaligned by 10 ° to
bike's centre line (like 2)
Height arch (value C) 7 cm 7 cm 7.5 cm 7.5 cm 10.5 cm 8 cm 12 cm
Offset seal seating (value D) 0 mm (flush) 0 mm (flush) 0 mm (flush) 0 mm (flush) 0 mm (flush) recessed by 30 mm 0 mm (flush) 0 mm (flush)
Exhaust pipe support
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
pipe clip mounted at lower engine mount bolt lower engine mount bolt lower engine mount bolt lower engine mount bolt lower engine mount bolt support at gearbox support at gearbox support bracket at frame
support length (value A) >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 184 mm 168 mm >doesn't exist<
Silencer
silencer analysis (German)
more videos and pictures
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Silencer type fish tail, black fish tail, black fish tail fish tail swallow tail torpedo long torpedo long torpedo
length 53 cm 53 cm 53 cm 53 cm 49 cm 58 cm 86 cm 86 cm
Inner diameter inlet
(manifold outer diameter) 		36 mm 36 mm 36 mm 36 mm 36 mm 30 mm 36 mm 36 mm
Tailpipe inner measurement 7 mm wide 7 mm wide 7 mm wide 7 mm wide 7 mm wide Ø 27 mm Ø 26 mm Ø 26 mm until 1963
then Ø 28 mm
Mounting bracket lengthways
in the middle 		bracket lengthways
in the middle 		bracket lengthways
in the middle 		bracket near back end bracket near back end M8x1 closed insert nut bracket near front end bracket near front end
Mounting point at frame
(all lower left corner) 		hole at axle eye hole at axle eye hole at axle eye shock absorber support shock absorber support dual-tapered bushing in the frame
in front of shock absorber support 		bushing outside the frame bushing outside the frame
Clamp, outer diameter >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< yes, ca. Ø 34 mm yes, ca. Ø 38 mm yes, ca. Ø 38 mm
Depth tailpipe ca. 28 cm ca. 36 cm
Crankcase
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Internal designation engine 220/1 223/1 224/1 224/2 224/3 224/4 226/1 226/2
Engine numbers 100 001 - 105 004 106 001 - 114 021 200 001 - 212 007 220 001 - 243 400 245 001 - 283 650 284 001 - 331 705 340 001 - 370 242 372 001 - 387 364
Camshaft bearing housing,
oil dip stick 		completely hidden
bulged right side! 		completely hidden
bulged right side! 		bulged
curved 		bulged
curved 		bulged
curved
from no. 277 632 both like R25/3 		straight down
straight 		straight down
straight 		straight down
straight
Lower engine mounting,
both sides symmetrical 		cylindrical for stud (like 1) cylindrical for stud (like 1) cylindrical for stud (like 1) cylindrical for stud (like 1) cylindrical for stud (like 1) entry funnel-like for rubber cones
then cylindrical for
spacer bushing (like 2) 		entry funnel-like for rubber cones
then cylindrical for
spacer bushing (like 2) 		only residual traces (like 3)
completely different solution
Feed hole for additional lubrication
cylinder, off side just below cylinder
base gasket on the inside 		no no no no no no yes yes
Cover oil-pump drive shaft M24x1.5 M24x1.5 M24x1.5 M24x1.5 M24x1.5
from no. 277 632 M26x1.5 		M26x1.5 M26x1.5 M26x1.5
Diameter bearing seat rear crankshaft bearing (main bearing) 62 mm (for 6206) 62 mm (for 6206) 62 mm (for 6206) 62 mm (for 6206) 62 mm (for 6206) 62 mm (for 6206) 72 mm (for 6207) 72 mm (for 6207)
Cylinder
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27 R50
Cylinder spigot diameter (value A) >doesn't exist< >doesn't exist< 74.0 mm 74.0 mm 74.0 mm 74.0 mm 78.0 mm 78.0 mm 78.0 mm
Centreing collar height (value B) >doesn't exist< >doesn't exist< 4.0 mm 4.0 mm 4.0 mm 4.0 mm 4.0 mm 4.0 mm 3.5 mm
Cylinder height (value C) 81.0 mm 81.0 mm 97.0 mm 97.0 mm 97.0 mm 97.0 mm 87.5 mm 87.5 mm 97.0 mm
Skirt height (value D) 54 mm 54 mm 22.5 mm 22.0 mm 22.0 mm 30.0 mm 38.0 mm 38.0 mm 25.0 mm
Groove (E),
number of oiling drills 		>doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 1 below oil pipe
no groove 		2, 1st below oil pipe
2nd opposite
connected via groove 		2
skirt diameter (value F) fit area 77.8 mm
below 66.7 mm 		fit area 76.0 mm
below 73.0 mm 		fit area 76.0 mm
below 74.0 mm 		fit area 76.0 mm
below 74.0 mm 		fit area 76.0 mm
below 74.0 mm 		fit area 76.0 mm
below 75.0 mm 		fit area 76.0 mm
below 75.0 mm 		fit area 80.0 mm
below 78.0 mm
Number of cooling fins 7 7 9 9 9 9 7 7 9
Cylinder head fastening 4 holes through
top two fins 		4 holes through
top two fins 		4 through holes 4 through holes 4 through holes 4 blind holes 4 blind holes 4 blind holes
Diameter cylinder between
fins 5 and 6 (from bottom)
(value G) 		82 mm 88 mm >no such gap< >no such gap< >no such gap< >no such gap< >no such gap< >no such gap< >no such gap<
Diameter oil pipe (value H) separate part separate part 6 mm (inner 4 mm) 6 mm (inner 4 mm) 6 mm (inner 4 mm) 6 mm (inner 4 mm) 6 mm (inner 4 mm) 8 mm (inner 6 mm)
Fins outline like 2 like 1 (but with gap) like 1 like 1 like 1 like 1 like 1 like 1
Cylinder head
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Colour silver silver silver silver silver
from no. 263 051 black 		black silver silver
Spark plug position right side right side left side left side left side left side right side right side
Third cooling fin from top unseparated unseparated in- and outtake separated
with "window" 		in- and outtake separated
with "window" 		in- and outtake separated
with "window"
from no. 267 301 unseparated 		unseparated unseparated unseparated
Lowest fin on carb side separated from flange integrated into carb flange
Number of pins per valve cap 2 2 2 2 1 1 1 1
Combustion chamber form round round round round round narrowed in the middle, "flat 8" Hemispherical Ø 60 mm Hemispherical Ø 60 mm
"Nose" with 2 stud bolts M8
above intake (engine suspension) 		no no no no no no late machines with "nose"
but without stud bolts 		yes
Intake diameter from carb 18 mm 20 mm 22 mm 24 mm 22 mm 24 mm 26 mm 26 mm
Carb mounting studs
thread x distance 		M6 M6 M6 M8 x 48 mm M8 x 48 mm M8 x 48 mm M8 x 53 mm M8 x 53 mm
Cylinder head screws stud bolts in cylinder head stud bolts in cylinder head with rocker arm bearing support
on long hex 		with rocker arm bearing support
on short hex and bushings 		"Normal" fit bolts WS14 "Normal" fit bolts WS14 "Normal" fit bolts WS14 "Normal" fit bolts WS14
Rocker arm bearing support integrally cast integrally cast on top of cylinder head screws on top of cylinder head screws on top of bushings
for rocker arm bearings 		on top of bushings
for rocker arm bearings 		on top of bushings
for rocker arm bearings 		on top of bushings
for rocker arm bearings
Rocker arm lubrication oil tube oil tube oil tube oil tube oil tube through bushings for rocker arm bearings through bushings for rocker arm bearings through bushings for rocker arm bearings
Rocker covers
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Concept one cover, central bolt one cover, central bolt two covers, gripping yoke two covers, gripping yoke two covers, gripping yoke two covers, gripping yoke two covers, gripping yoke two covers, gripping yoke
Number of cooling fins 0 0 3 3 2 2 2 2
Number of casted lugs with hole inside 0 0 2 2 1 1 1 1
Gripping yoke rest >doesn't exist< >doesn't exist< recess recess platform platform platform platform
Width of bottom cooling fin >doesn't exist< >doesn't exist< 136 mm 125 mm 132 mm 132 mm 142 mm 142 mm
Oil sump
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Concept part of engine housing part of engine housing separate oil pan separate oil pan separate oil pan separate oil pan separate oil pan separate oil pan
Location sump drain plug at the front, left side at the front, left side right side, to the front right side, to the front first right side, to the front
then at the rear (transmission side) 		at the rear (transmission side) at the rear (transmission side) at the rear (transmission side)
Bearing plate
sketch

Diameter of flange fit in
crankcase Ø 116 mm
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Made of aluminium aluminium aluminium aluminium steel steel steel steel
Bearing 6206 in bearing sleeve bearing sleeve bearing sleeve bearing sleeve bearing plate bearing plate bearing plate bearing plate
Number of ears 6 6 6, from no. 204 213
5 ("a" dropped) 		5 ("a" dropped) 5 ("a" dropped) 5 ("a" dropped) 5 ("a" dropped) 5 ("a" dropped)
Design ear "f" like the others (1) like the others (1) like the others (1) like the others (1) like the others (1) like the others (1) like the others (1) reinforced (2)
Flange thickness 5 mm 5 mm 5 mm 5 mm 6 mm 5 mm
Generator cover
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Made of sheet metal sheet metal sheet metal sheet metal sheet metal sheet metal sheet metal cast aluminium
Design and height "dish" "dish" "pot" "pot", 55 mm "pot", 55 mm "pot", 55 mm "pot", 55 mm "pot", 35 mm
Diameter Ø 127 mm Ø 127 mm ... Ø 147 mm Ø 147 mm Ø 147 mm Ø 147 mm Ø 150 mm
Attaching screws go through 2 holes, horizontal in line
on flat area 		2 holes, horizontal in line
on flat area 		2 holes, horizontal in line
on flat area 		2 holes, vertical in line
on flat area, 90 mm apart 		2 holes, vertical in line
on flat area, 90 mm apart 		2 holes, vertical in line
on flat area, 90 mm apart 		2 holes, vertical in line
on flat area, 90 mm apart 		3 eyes at the rim
120 ° at 12, 4, 8 'o clock
crankshaft
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Diameter rear pivot 30 mm 30 mm 30 mm 30 mm 30 mm 30 mm 35 mm 35 mm
Diameter crank pin 25 mm 32 mm 32 mm 32 mm 32 mm 32 mm
Balance weight form 1 1 1 2 2 2 3 with aluminium rod
2 with steel piston rod 		2
Sprocket wheel
Dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design like 1(symmetrical) like 1(symmetrical) like 1(symmetrical) like 1(symmetrical) like 2(collar towards big end) like 2(collar towards big end)
Bore diameter (value A) 20 mm 20 mm 20 mm 20 mm 30 mm 30 mm
Length through bore (value B) 14 mm 14 mm 14 mm 14 mm 20 mm 20 mm
Hub outside diameter (value C) 35 mm 35 mm 35 mm 35 mm 38 mm 38 mm
Outer diameter "collar" (valued D) >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 42 mm 42 mm
Oil slinger plate
dimensioned sketch
Note: for R26 depending on crankshaft (see there) balance weight form
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
outer spigot diameter (value A) No oil slinger plate
present 		No oil slinger plate
present 		17.7 mm or
18.4 mm 		18.4 mm 18.4 mm 18.4 mm (weight like 3)
17.9 mm (weight like 2) 		17.9 mm
Distance of holes for
crank shaft and retaining screw (value B) 		>doesn't exist< >doesn't exist< 8.5 mm 8.5 mm 8.5 mm 8.5 mm (weight like 3)
10.5 mm (weight like 2) 		10.5 mm
Piston rod
Dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Centre distance (value A) 136 mm 136 mm 136 mm 136 mm 136 mm 136 mm 125 mm 120 mm
Ø small end bore (value B) 16 mm 16 mm 18 mm 18 mm 18 mm 18 mm aluminium rod 18 mm
steel rod 20 mm 		20 mm
Ø big end bore (value C) 39 mm 46 mm 46 mm 46 mm aluminium rod 32 mm
steel rod 42 mm 		42 mm
Big end bearing roller bearing in cage roller bearing in cage roller bearing in cage
(rollers Ø 7 mm) 		roller bearing in cage
(rollers Ø 7 mm) 		roller bearing in cage
(rollers Ø 7 mm) 		roller bearing in cage
(rollers Ø 7 mm) 		aluminium: plain bearing
steel: roller bearing in cage
(rollers Ø 5 mm) 		roller bearing in cage
(rollers Ø 5 mm)
Made from ... steel steel steel steel steel steel aluminium or steel
see crankshaft 		steel
Piston
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Diameter (start - steps - max size) 60 mm 68 mm - 0.5 mm - 70 mm 68 mm - 0.5 mm - 70 mm 68 mm - 0.5 mm - 70 mm 68 mm - 0.5 mm - 70 mm 68 mm - 0.5 mm - 70 mm 68 mm - 0.5 mm - 70 mm 68 mm - 0.5 mm - 70 mm
Compression height (value A) 34 mm 34 mm 31 mm 31 mm 31 mm 31 mm 32 mm 37 mm
from no. 385 083 38.6 mm
Height pop-up (value B) 0 mm 0 mm 3.5 mm 3.5 mm 3.5 mm 3.5 mm 9.5 mm 14.2 mm
from no. 385 083 9.7 mm
Diameter gudgeon pin (value C) 16 mm 16 mm 18 mm 18 mm 18 mm 18 mm aluminium rod 18 mm
steel rod 20 mm 		20 mm
Disc flywheel
dimensioned sketch


(All: Ø 183 mm)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Height (value A) 34.4 mm 48 mm 48 mm 48 mm 39 mm 39 mm
Diameter seat
shaft sealing ring (value B) 		45 mm 45 mm 45 mm 45 mm 52 mm 52 mm
Clutch spring receiver >nothing specific< three holes for coil springs three holes for coil springs three holes for coil springs three holes for coil springs >nothing specific< >nothing specific< >nothing specific<
Ignition timing indicators none none none none OT stamped
264 251 also
steel balls ind. F/S 		OT stamped
steel balls ind. F/S 		F/S/OT stamped F/S/OT stamped
Clutch spring(s)
sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Spring type 1 coil spring (Ø 57 mm) 3 coil springs 3 coil springs (Ø 30 mm) 3 coil springs (Ø 30 mm) 3 coil springs (Ø 30 mm) diaphragm spring
18 fingers (like 1) 		diaphragm spring
18 fingers (like 2) 		diaphragm spring
18 fingers (like 2)
Length/ height 48 mm 38+1 mm 38+1 mm 38+1 mm 18 mm (new) 14 mm (new) 14 mm (new)
Positioning spring(s) central, truncated cone
at pressure plate 		aligned to clutch lining
three recesses each in flywheel
and pressure plate 		aligned to clutch lining
three recesses each in flywheel
and pressure plate 		aligned to clutch lining
three recesses each in flywheel
and pressure plate 		aligned to clutch lining
three recesses each in flywheel
and pressure plate 		"inside" flywheel
fingers towards pressure plate 		"inside" flywheel
fingers towards pressure plate 		"inside" flywheel
fingers towards pressure plate
Pressure plate
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Height 10 mm 18 mm 15 mm 15 mm
Disc centre square hole for thrust rod square hole for thrust rod square hole for thrust rod square hole for thrust rod square hole for thrust rod square hole for thrust rod conical hole for thrust rod conical hole for thrust rod
Design, joining method single piece single piece single piece single piece single piece two pieces, riveted two pieces, spot-welded two pieces, spot-welded
Clutch spring receiver central truncated cone aligned to clutch lining
three recesses 		aligned to clutch lining
three recesses 		aligned to clutch lining
three recesses 		aligned to clutch lining
three recesses 		reinforcement disc
for fingers 		reinforcement disc
for fingers 		reinforcement disc
for fingers
Clutch plate
All diameter 150 mm
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Overall thinkness 7 mm 7 mm 7 mm 7 mm 7 mm 5 mm 5 mm 5 mm
Pressure ring
Sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design outer rim ... smooth (like 1),
3 holes close to rim for bolts 		smooth (like 1),
3 holes close to rim for bolts 		smooth (like 1),
3 holes close to rim for bolts 		smooth (like 1),
3 holes close to rim for bolts 		smooth (like 1),
3 holes close to rim for bolts 		6 "eyelets" (like 2),
each with a bolt hole 		6 "eyelets" (like 2),
each with a bolt hole 		6 "eyelets" (like 2),
each with a bolt hole
Camshaft
All camshafts 6 mm cam lift
valve timing at 2 mm valve clearance
(acc. to measuring specs)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Total length 113 mm 113 mm 117 mm 117 mm 117 mm 117 mm 117 mm 180 mm
Front end centering for
sprocket puller 		centering for
sprocket puller 		M8 internal thread
for breather disc screw 		M8 internal thread
for breather disc screw 		M8 internal thread
for breather disc screw 		M8 internal thread
for breather disc screw 		M8 internal thread
for breather disc screw 		thread M6 for mounting nut
of centrifugal governor
cam width 16 mm 16 mm 20 mm 20 mm 20 mm 20 mm 20 mm 12 mm
Intake valve opens/ closes 11° after TDC / 29° after BDC 11° after TDC / 29° after BDC 6° after TDC / 34° after BDC 6° after TDC / 34° after BDC 6° after TDC / 34° after BDC 6° after TDC / 34° after BDC 6° after TDC / 34° after BDC 4° before TDC / 23° after BDC
Outlet valve opens/ closes 29° before BDC / 11° before TDC 29° before BDC / 11° before TDC 34° before BDC / 6° before TDC 34° before BDC / 6° before TDC 34° before BDC / 6° before TDC 34° before BDC / 6° before TDC 34° before BDC / 6° before TDC 43° before BDC / 16° before TDC
Breather
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Diameter x height Ø 34 x 22 mm Ø 34 x 22 mm Ø 34 x 22 mm Ø 34 x 22 mm Ø 34 x 22 mm Ø 34 x 22 mm Ø 34 x 22 mm Ø 30 x 17 mm
Number of pins 2 2 1 1 1 1 1 1
Oil pump
supply rate of 10 mm-version
2000 ml/min at 7200 rpm
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Height gear wheels 8 mm 8 mm 10 mm 8 mm
10 mm from no. 220 076 		10 mm 10 mm 10 mm 10 mm
15 mm from no. 381 133
Length drive shaft 200.5 mm 200.5 mm 162.5 mm 162.5 mm 162.5 mm 162.5 mm 162.5 mm 162.5 mm
152.5 mm from no. 381 133
Height gear wheel housing alone 26.5 mm 26.5 mm 26.5 mm 26.5 mm 26.5 mm 26.5 mm
36.5 mm from no. 381 133
Oil dipstick
dimensioned sketch


(offset of up to 2 mm possible)
all thread M26x1.5
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Head style Hexagon head WS22 Hexagon head WS22 Hexagon head WS21 Hexagon head WS21 Winged nut Winged nut Winged nut Winged nut
Total length stick (value A) 125.5 mm 125.5 mm 229 mm 229 mm 229 mm 229 mm 229 mm 229 mm
Oil level mark Max (value B) 80 mm (Max 1½ l) 80 mm (Max 1½ l) 155 mm (Max 1½ l) 155 mm (Max 1½ l)
from no. 222 511
175 mm (Max 1¼ l) 		175 mm (Max 1¼ l)
from no.268 851 ¼l marks 		175 mm (Max 1¼ l) 175 mm (Max 1¼ l) 175 mm (Max 1¼ l)
1st intermediate (value C) 103 mm (1¼ l) 103 mm (1¼ l) 195 mm (1 l) 195 mm (1 l) 195 mm (1 l) 195 mm (1 l) 195 mm (1 l) 195 mm (1 l)
2nd intermediate (value D) >doesn't exist< >doesn't exist< 205 mm (¾ l) 205 mm (¾ l) 205 mm (¾ l) 205 mm (¾ l) 205 mm (¾ l) 205 mm (¾ l)
Oil level mark Min (value E) 109 mm (Min 1 l) 109 mm (Min 1 l) 222 mm (Min ½ l) 222 mm (Min ½ l) 222 mm (Min ½ l) 222 mm (Min ½ l) 222 mm (Min ½ l) 222 mm (Min ½ l)
Tappets
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Tappets no. of windows 0 0 4 4 4 or 2 4 or 2 4 or 2 2
Camshaft contact area slightly convex slightly convex flat flat flat flat flat convex
Drill holes for lubrication 1 1 2 2 0 0 0 0
Push rods
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Push rod length (± 2 mm) 224.5 mm (+spring) 224.5 mm (+spring) 185 mm 185 mm 185 mm 185 mm 175 mm 175 mm
Rocker shafts
Sketch


(All: length 82 mm, Ø 13 mm)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Setup solid solid blind hole tube blind hole tube blind hole tube solid solid solid
Lubrification rocker arms 4 holes with Ø 2.5 mm
two on each side (like 1) 		4 holes with Ø 2.5 mm
two on each side (like 1) 		4 holes with Ø 2.0 mm
two on each side (like 1) 		flat top (12.2 mm)
conduits at bolts (like 2) 		flat top (12.2 mm)
conduits at bolts (like 2) 		flat top (12.2 mm)
conduits at bolts (like 2)
Also used in ... ... R51/2 R51/2 R51/3, R67/2 ... ... ...
Rocker arms
sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Valve clearance adjusting screws on valve side on valve side on valve side on valve side on pushrod side
M8x1, AF 11 mm! 		on pushrod side
M8x1, AF 11 mm! 		on pushrod side
M8x1, AF 11 mm! 		on pushrod side
M8x1, AF 11 mm!
Form pushrod arm from above curved (like 1) curved (like 1) curved (like 1) curved (like 1) straight (like 2) straight (like 2) straight (like 2) straight (like 2)
Bearing linings three-part, loose three-part, loose two-part, loose two-part, pressed two-part, pressed two-part, pressed
Also used in ... ... R51/2 R51/2 R51/3-R68 ... ... ...
Valves
dimensioned sketch


(All: length 87 mm, shaft Ø 7 mm)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Diameter intake/ exhaust valve both valves identical both valves identical 34 mm/ 32 mm 34 mm/ 32 mm 32 mm/ 32 mm 34 mm/ 32 mm 34 mm/ 32 mm 34 mm/ 32 mm
Collet area for ... long collets (like 1) long collets (like 1) long collets (like 1) long collets (like 1) long collets (like 1) long collets (like 1) set off short collets
short collets from no. 364 872
(both like 2) 		short collets (like 2)
grooved from no. 385 265 (like 3)
Valve guides
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
length valve guide (value A) 45 mm 43 mm 43 mm 43 mm 43 mm 52 mm,
50 mm from no. 364 872 		50 mm
projecting length top (value B) 12 mm 11.2 mm 11.2 mm 11.2 mm 11.2 mm 19 mm,
17 mm from no. 364 872 		17 mm,
15.2 mm from no. 385 265
Valve springs
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
inner spring
diameter x length x wire gauge 		Ø 20.5 mm x 27 mm Ø 20.5 mm x 27 mm Ø 23.8 mm x 37.5 mm x 2.8 mm Ø 23.8 mm x 37.5 mm x 2.8 mm Ø 23.8 mm x 37.5 mm x 2.8 mm Ø 23.8 mm x 37.5 mm x 2.8 mm Ø 23.8 mm x 37.5 mm x 2.8 mm Ø 23.8 mm x 37.5 mm x 2.8 mm
outer spring
diameter x length x wire gauge 		Ø 32 mm x 32 mm Ø 32 mm x 32 mm Ø 34.5 mm x 43 mm Ø 34.5 mm x 46 mm x 3.5 mm Ø 34.5 mm x 46 mm x 3.5 mm Ø 34.5 mm x 46 mm x 3.5 mm Ø 34.5 mm x 42.3 mm x 3.8 mm Ø 34.5 mm x 42,3 mm x 3.8 mm
Valve collets and retainers
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design like 1 like 1 like 1 like 1 like 1 like 1 like 2,
from no. 364 872 like 3 		like 3,
from no. 385 265 like 4
valve collet type long collets long collets long collets long collets long collets long collets off set short collets,
short collets from no. 364 872 		short collets
grooved from no. 385 265
collet length (value A) 8 mm 8 mm 8 mm 8 mm 8 mm 8 mm 6.5 mm,
6 mm from no. 364 872 		6 mm,
10.65 mm from no. 385 265
retainer height (value B) 14 mm 14 mm 15 mm 15 mm 15 mm 15 mm 6.5 mm,
9.6 mm from no. 364 872 		9.6 mm,
10.3 mm from no. 385 265
retainer diameter (value C) 32.8 mm 32.8 mm 32.8 mm 32.8 mm 32.8 mm 32.8 mm
32.0 mm from no. 385 265
hole diameter(value D) 8.25 mm 8.25 mm 8.9 mm 8.9 mm 8.9 mm 8.9 mm 9.2 mm,
8.9 mm from no. 364 872 		8.9 mm,
9.0 mm from no. 385 265
Generator
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Model Bosch F1/LK50/6/1800R1
6V/50W 		Bosch F1/LK50/6/1800R1
6V/50W 		Bosch 6V/45W Bosch 6V/45-60W Noris ZLZ 45/60 Noris ZLZ 45/60
from no.286 497 Noris ZLZ60/6/1600/L 		Noris ZLZ 60/6/1600 1/L Bosch LJ/CJE 60/6/1800 R 5
Print rotor and
engaging slot for governor 		520/1Z
no groove 		520/1Z
no groove 		ZLZ161/1Z ZLZ161/1Z
from no. 286 497 ZLZ161/2Z 		ZLZ161/2Z LJAN2T1Z or
3 104 014 403
Width brush springs 3 mm 3 mm 3 mm 3 mm 3 mm 4 mm
ignition timing adjustment
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Method manual adjustment
(lever at handle bar) 		manual adjustment
(lever at handle bar) 		centrifugal governor (CG) centrifugal governor (CG) centrifugal governor (CG) centrifugal governor (CG) centrifugal governor (CG) centrifugal governor (CG)
Shape (CG) >not applicable< >not applicable< no notches no notches no notches two notches two notches no notches
BMW-number (CG)
(1|2 indicates 1 or 2) 		>not applicable< >not applicable< --- --- --- ZG209/13|16|23|26z ZG209/13|16|23|26z ZV SV 2Z 1Z
Bosch number (CG) >not applicable< >not applicable< --- --- --- 1 119 999 118|122|126 1 119 999 118|122|126 1 237 120 035
Gear box general
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Number of speeds 3 3 4 4 4 4 4 4
Hand gear change lever no no yes yes yes no no no
Coupling jacket no no no no no no yes yes
Mounting holes on engine side 6.3 mm 6.3 mm 6.3 mm 8.5 mm 8.5 mm 8.5 mm 8.5 mm 8.5 mm
Bolted-on brackets underneath no no no no no no no yes
Bulge for left selector shaft 20 mm 5 mm 5 mm 5 mm 5 mm 5 mm
Design shift fork bolts >doesn't exist< >doesn't exist< slotted pan head bolts slotted pan head bolts slotted pan head bolts
from no 272 479
Allen bolts with inserts
from no 274 568 Allen bolts 		Allen bolts Allen bolts Allen bolts
Neutral indicator switch no no no no yes yes yes yes
Bearing block for clutch release lever integrally cast integrally cast integrally cast Steel frame, bolted Steel frame, bolted Steel frame, bolted integrally cast
(stronger than R24) 		integrally cast
(stronger than R24)
Transmission housing cover
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Neutral indicator switch no no no no yes yes yes yes
Mounting point for
Coupling jacket 		no no no no no no yes yes
Bearing block for clutch release lever
width at bolt level 		integrally cast
20 mm 		integrally cast
20 mm 		integrally cast
48 mm 		Steel frame, bolted Steel frame, bolted Steel frame, bolted integrally cast
(stronger than R24) 		integrally cast
(stronger than R24)
Shifting mechanism
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Detenting notches on shift lever shift lever cam plate cam plate cam plate cam plate cam plate cam plate
Number of notches
(gear sequence, N=neutral) 		4 (1-N-2-3) 4 (1-N-2-3) 6 (1-N-2-3-N-4) 6 (1-N-2-3-N-4) 6 (1-N-2-3-N-4)
from no. 273 005
5 (1-N-2-3-4) 		5 (1-N-2-3-4) 5 (1-N-2-3-4) 5 (1-N-2-3-4)
Contact rivet for
neutral indicator 		no no no no yes
only N between 1 and 2 		yes yes yes
Kick start shaft
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27 R50
Number of teeth 9 9 11½ 11½ 11½ 11½ 11½ 11½ 9½
Feeler spring no no no (like 1.1) no (like 1.1) no (like 1.1)
from no. 277 350 yes (like 1.2) 		yes (like 1.2) yes (like 1.2) yes (like 1.2)
"Orientation" wedge bolt area
Eppo's how-to measure
(German) 		7¾ teeth (like 2.1) 7¾ teeth (like 2.1) 7¾ teeth (like 2.1) 7¾ teeth (like 2.1) 8¾ teeth (like 2.2) 8¾ teeth (like 2.2)
Primary shaft
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27 R50
Length splines (value A) 24.5 mm 24.5 mm 24.5 mm 24.5 mm 28.6 mm 28.6 mm 22,5 mm
Thrust rod
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design one piece one piece one piece one piece
from no. 227 981 three pieces 		three pieces three pieces one piece one piece
Total length 215 mm 215 mm 205 mm 205 mm 205 mm 205 mm 209.5 mm 209.5 mm
Section A (length x diameter) 17 mm x Ø 5.0 mm 17 mm x Ø 5.0 mm 18 mm x Ø 6.1 mm 18 mm x Ø 6.1 mm 18 mm x Ø 6.1 mm 18 mm x Ø 6.1 mm 17.8 mm x Ø 6.0 mm 17.8 mm x Ø 6.0 mm
Section B (length x diameter) 193.0 mm x Ø 7.0 mm 193.0 mm x Ø 7.0 mm 25 mm x Ø 8.4 mm 25 mm x Ø 8.4 mm 25 mm x Ø 8.4 mm 25 mm x Ø 8.4 mm 21.0 mm x Ø 8.3 mm 21.0 mm x Ø 8.3 mm
Section C (length x diameter) >doesn't exist< >doesn't exist< 13 mm x Ø 5 mm 28 mm x Ø 5 mm (visible 13 mm) 28 mm x Ø 5 mm (visible 13 mm) 28 mm x Ø 5 mm (visible 13 mm) 18.0 mm x Ø 5.2 mm 18.0 mm x Ø 5.2 mm
Section D (length x diameter) >doesn't exist< >doesn't exist< 141.5 mm x Ø 7.5 mm 141.5 mm x Ø 7.5 mm 141.5 mm x Ø 7.5 mm 141.5 mm x Ø 7.5 mm 148.5 mm x Ø 7.5 mm 148.5 mm x Ø 7.5 mm
Section E (design and measurements) square
5 mm x 4.9 mm 		square
5 mm x 4.9 mm 		square 8 mm x 4.9 mm square 8 mm x 4.9 mm square 8 mm x 4.9 mm square 8 mm x 4.9 mm cone 4 mm x 60° cone 4 mm x 60°
Spacer
dimensioned sketch
all diameter 23 mm
dimensions R50-R69S see R50
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27 R50
Design (ring groove!) like 1 (rectangular) like 1 (rectangular)
231 240 like 2 (stepped) 		like 2 (stepped) like 2 (stepped) like 2 (stepped) like 2 (stepped) like 2 (stepped)
Total length (value A) 25 mm 25 mm 25 mm 25 mm 25 mm 25 mm 26.5 mm
Length "thick part" (value B) 16.5 mm 16.5 mm 16.5 mm 16.5 mm 16.5 mm 16.5 mm 18.5 mm
cross-section gasket like 1 (rectangular) like 1 (rectangular)
231 240 like 2 ("Y") 		like 2 ("Y") like 2 ("Y") like 2 ("Y") like 2 ("Y") like 2 ("Y")
Clutch release lever
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
length (value A)
different reference points! 		145 mm 145 mm 142 mm 128 mm 128 mm 128 mm 128 mm 128 mm
Bowden cable side M8 thread for adjuster M8 thread for adjuster M8 thread for adjuster forked for bowden cable nipple forked for bowden cable nipple forked for bowden cable nipple forked for bowden cable nipple forked for bowden cable nipple
deviation angle α 0 ° 0 ° 0 ° 15 ° 15 ° 15 ° 15 ° 15 °
Diameter hole bolt
for holding pin 		6 mm 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm
Holding pin design with endplate and hole
for split pin (like 1) 		with endplate and hole
for split pin (like 1) 		with two grooves, "inner"
for split pin (like 2) 		with endplate and hole
for split pin (like 1) 		with endplate and hole
for split pin (like 1) 		with endplate and hole
for split pin (like 1) 		with two grooves, "inner"
for split pin (like 2) 		with two grooves, "inner"
for split pin (like 2)
Holding pin length 26.5 mm 26.5 mm 56 mm 37.5 mm
(45.5mm for carrier) 		37.5 mm
(45.5mm for carrier) 		37.5 mm
(45.5mm for carrier) 		56 mm 56 mm
Adjustment screw lever C >doesn't exist< >doesn't exist< M8 x 25 mm M8 x 15 mm M8 x 15 mm M8 x 15 mm M8 x 25 mm M8 x 25 mm
Adjustment screw cable D design slotted full length
with latching groove(s) 		slotted full length
with latching groove(s) 		slotted full length
with latching groove(s) 		>doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist<
Adjustment screw D thread x length M8x1 x 36 mm M8x1 x 36 mm M8x1 x 36 mm >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist<
Foot shift lever
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Material steel, nickel plated steel, nickel plated steel, black coated steel, chrome-plated steel, chrome-plated steel, chrome-plated steel, chrome-plated steel, chrome-plated
Kick start lever
sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Material steel, nickel plated steel, nickel plated steel, black coated steel, chrome-plated steel, chrome-plated aluminium aluminium aluminium
Arm cross-section (A-B) and
wider "foot"
for rubber bumper 		like 1.1
no 		like 1.1
no 		like 1.1
no 		like 1.2
yes,
T-shaped 		like 1.3
yes,
slightly T-shaped 		like 1.4
yes,
triangular 		like 1.5
yes,
explicitly T-shaped 		like 1.5
yes,
explicitly T-shaped
Transition from shaftmount
to pedal arm 		organic (like 2.1) organic (like 2.1) organic (like 2.1) organic (like 2.1) organic (like 2.1) organic (like 2.1) straight (like 2.2) straight (like 2.2)
Wedge-hole to pedal arm parallel parallel perpendicular perpendicular perpendicular perpendicular perpendicular perpendicular
footpeg form round peg with rubber (like 3.1)
or tube wall segment (like 3.2) 		tube wall segment with
linear grooves (like 3.2) 		tube wall segment with
linear grooves (like 3.2) 		tube wall segment with
linear grooves (like 3.2) 		tube wall segment with
linear grooves (like 3.2) 		tube wall segment with
linear grooves (like 3.2) 		tube wall segment with
linear grooves (like 3.2) 		tube wall segment with
linear grooves (like 3.2)
Positioning
and locking 		serrated shaft and
tapered pin 		serrated shaft and
tapered pin 		wedge bolt wedge bolt wedge bolt wedge bolt wedge bolt wedge bolt
Flexible disc flanges
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Number of pins per flange 3, bolted on 3, bolted on 2, part of the flange 2, part of the flange 2, part of the flange 2, part of the flange 2, part of the flange 2, part of the flange
Connection flexible disc two steel plates with
three pins each, 60° offset
flanges bolted to pins 		two steel plates with
three pins each, 60° offset
flanges bolted to pins 		two flanges with
two pins each, 90° offset
pins straight into the disc 		two flanges with
two pins each, 90° offset
pins straight into the disc 		two flanges with
two pins each, 90° offset
pins straight into the disc 		two flanges with
two pins each, 90° offset
pins straight into the disc 		two flanges with
two pins each, 90° offset
pins straight into the disc 		two flanges with
two pins each, 90° offset
pins straight into the disc
Flexible disc
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Flexible disc Rubber disc ("puck") Rubber disc ("puck") Rubber disc ("puck") Rubber disc ("puck") Rubber disc ("puck") Rubber disc ("puck") Rubber disc ("puck")
from no 350 000
Vulkollan "cross" 		Vulkollan "cross"
Number of holes for flanges 6 6 4 4 4 4 4 4
Height 28 mm 28 mm 26 mm 26 mm 26 mm 26 mm
from Jan 1955 17 mm 		all 17 mm 17 mm
Rubber washer required
thickness x outer Ø x inner Ø 		no no no no no no
from January 1955 yes
5mm x 32mm x 17mm 		yes
5mm x 32mm x 17mm 		yes
5mm x 32mm x 17mm
Cover ring
All made from steel with 24 mm width,
on the inside centered groove
for catch ring
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Surface >doesn't exist< >doesn't exist< chrome-plated chrome-plated chrome-plated chrome-plated zinc-plated zinc-plated
Outer diameter (material thickness) >doesn't exist< >doesn't exist< Ø 102 mm (3.5 mm) Ø 102 mm (3.5 mm) Ø 102 mm (3.5 mm) Ø 102 mm (3.5 mm) Ø 102 mm (3.5 mm)
from no 350 000 Ø 105 mm (5 mm) 		Ø 105 mm (5 mm)
Edges >doesn't exist< >doesn't exist< outer ones softened outer ones softened outer ones softened outer ones softened outer ones softened
from no 350 000
inner ones angled by 30 °, 2.5 mm 		inner ones angled by 30 °, 2.5 mm
Cardan drive
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Flexible disc flange Press-fitted Press-fitted Press-fitted Press-fitted Press-fitted Press-fitted Longitudinal teeth with
round nut 		Longitudinal teeth with
round nut
Rear wheel drive side Pinion dog (internal serration)
press-fitted 		Pinion dog (internal serration)
press-fitted 		Pinion dog (internal serration)
press-fitted 		Cardan joint (yoke)
one-piece forged 		Cardan joint (yoke)
one-piece forged 		Cardan joint (yoke)
one-piece forged 		"Pot" (internal longitudinal teeth)
one-piece forged 		"Pot" (internal longitudinal teeth)
one-piece forged
U-joint protecting bell
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Length (value A) >doesn't exist< >doesn't exist< >doesn't exist< 65 mm 65 mm 65 mm >doesn't exist< >doesn't exist<
Collar length (value B) >doesn't exist< >doesn't exist< >doesn't exist< 29 mm 29 mm 14 mm >doesn't exist< >doesn't exist<
Gear and crown wheel
Heiko's parts-comparison (German)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Teeth bevel gear/ crown wheel
(type: solo = Klingelnberg
side car = Gleason) 		11 / 46 11 / 46 11 / 46 solo or
8 / 34 solo 		6 / 27 solo
5 / 26 side car 		6 / 27 solo
7 / 36 or 5 /26 side car 		6 / 25 solo
5 / 24 side car 		6 / 25 solo
5 / 26 side car 		6 / 25 solo
6 / 27 solo from no. 379 495
5 / 26 side car
Crown wheel mark
under bearing wheel side 		225/1 225/3 226/1 226/2
Height of crown wheel
to top edge gearing 		33 mm 33 mm 41 mm 41 mm
Length of pinion shaft
incl. bevel gear 		110 mm 110 mm 136 mm 136 mm
Rear axle gearbox
Sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Diameter wheel side cover-plate
(look from above) 		191 mm 191 mm 191 mm 196 mm (like 1) 196 mm (like 1)
later 218 mm (like 2) 		218 mm (like 3) 218 mm 218 mm
Stepped wheel side cover-plate no no no yes (like 1) yes (like 1 or 2) no (like 3) no no
Drillhole for brake cam 12 mm 12 mm 12 mm 12 mm 12 mm 14 mm 14 mm 14 mm
Drive shaft side flange with 2 stud bolts flange with 2 stud bolts flange with 2 stud bolts threaded ring/ thread threaded ring/ thread threaded ring/ thread flange with 4 stud bolts flange with 4 stud bolts
Cover rear axle gearbox
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Equipped >doesn't exist< >doesn't exist< >doesn't exist< with suspension unit holder with suspension unit holder with suspension unit holder "smooth" with
8 mm hole at "1 o'clock"
for shock absorber 		"smooth" with
8 mm hole at "1 o'clock"
for shock absorber
Hole for slide bush >doesn't exist< >doesn't exist< >doesn't exist< Ø 26 mm Ø 26 mm Ø 29 mm >doesn't exist< >doesn't exist<
Rear axle holder
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Hole for slide bush >doesn't exist< >doesn't exist< >doesn't exist< Ø 26 mm Ø 26 mm Ø 29 mm >doesn't exist< >doesn't exist<
Clamping axle,
hole for clamping bolt 		>doesn't exist< >doesn't exist< >doesn't exist< rear slotted, Ø 10 mm
from no. 231 126
solid, Ø 20 mm 		solid, Ø 20 mm solid, Ø 20 mm >doesn't exist< >doesn't exist<
Axle clamping bolt
sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
bolt design (thread M10x1) >doesn't exist< >doesn't exist< >doesn't exist< half t-head bolt (like 1)
from no. 231 126
special with bushing (like 2) 		special with bushing (like 2) special with bushing (like 2) half t-head bolt (like 1) half t-head bolt (like 1)
Slide bush (Pertinax)
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Inner Ø x outer Ø x height >doesn't exist< >doesn't exist< >doesn't exist< 22 mm x 26 mm x 25 mm 22 mm x 26 mm x 25 mm 25 mm x 29 mm x 25 mm >doesn't exist< >doesn't exist<
Spring cover top
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Material >doesn't exist< >doesn't exist< >doesn't exist< coated steel, 1 mm coated steel, 1 mm I. aluminium, 1 mm
II. aluminium, 1 mm 		>doesn't exist< >doesn't exist<
Diameter (value A) >doesn't exist< >doesn't exist< >doesn't exist< 66.5 mm 66.5 mm I. 66 mm
II. 70 mm 		>doesn't exist< >doesn't exist<
Total length (value B) >doesn't exist< >doesn't exist< >doesn't exist< 69.5 mm 69.5 mm I. 91 mm
II. 91 mm 		>doesn't exist< >doesn't exist<
Diameter hole (value C) >doesn't exist< >doesn't exist< >doesn't exist< 27 mm 27 mm I. 29.5 mm
II. 29.5 mm 		>doesn't exist< >doesn't exist<
Spring cover bottom
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Material >doesn't exist< >doesn't exist< >doesn't exist< coated steel, 1 mm coated steel, 1 mm I. coated steel, 1 mm
II. coated steel, 1 mm 		aluminium, 1 mm aluminium, 1 mm
Diameter (value A) >doesn't exist< >doesn't exist< >doesn't exist< 60.5 mm 60.5 mm I. 60 mm
II. 64 mm 		92.5 mm 92.5 mm
Total length (value B) >doesn't exist< >doesn't exist< >doesn't exist< 70 mm 70 mm I. 91 mm
II. 91 mm 		60.4 mm 60.4 mm
Diameter hole (value C) >doesn't exist< >doesn't exist< >doesn't exist< 48 mm 48 mm I. 48 mm
II. 48 mm 		36.6 mm 36.6 mm
Grease cap (bottom)
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Material >doesn't exist< >doesn't exist< >doesn't exist< coated steel, 1 mm coated steel, 1 mm aluminium, 1 mm >doesn't exist< >doesn't exist<
Diameter (value A) >doesn't exist< >doesn't exist< >doesn't exist< 46.5 mm 46.5 mm 46 mm >doesn't exist< >doesn't exist<
Total length (value B) >doesn't exist< >doesn't exist< >doesn't exist< 48 mm 48 mm 44.5 mm >doesn't exist< >doesn't exist<
Diameter hole (value C) >doesn't exist< >doesn't exist< >doesn't exist< 20.2 mm 20.2 mm 23.5 mm >doesn't exist< >doesn't exist<
Suspension springs rear
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Length relaxed (± 2 mm) >doesn't exist< >doesn't exist< >doesn't exist< 129 mm 129 mm 164 mm solo
171 mm side car 		284 mm solo
272,5 mm side car 		284 mm solo
272,5 mm side car
Wire diameter >doesn't exist< >doesn't exist< >doesn't exist< 7.5 mm 7.5 mm 7,5 mm
8.0 mm side car 		6.5 mm solo
7.4 mm side car 		6.5 mm solo
7.4 mm side car
Spring diameter outer >doesn't exist< >doesn't exist< >doesn't exist< 55 mm 55 mm 56 mm solo 50 mm solo
51.9 mm side car 		50 mm solo
51.9 mm side car
Number of coils >doesn't exist< >doesn't exist< >doesn't exist< 9.5 linear 9.5 linear 10.5 both ends progr. solo 21 both ends progr. solo
19 linear side car 		21 both ends progr. solo
19 linear side car
Plunger post
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Total length (value A) >doesn't exist< >doesn't exist< >doesn't exist< 27,5 cm 28,5 cm 32,0 cm >doesn't exist< >doesn't exist<
Length to shoulder (value B) >doesn't exist< >doesn't exist< >doesn't exist< 25.5 cm 26.3 cm 30.0 cm >doesn't exist< >doesn't exist<
Diameter (value C) >doesn't exist< >doesn't exist< >doesn't exist< 21.8 mm 21.8 mm 24.8 mm >doesn't exist< >doesn't exist<
Diameter clamping (value D) >doesn't exist< >doesn't exist< >doesn't exist< 19.8 mm 19.8 mm 23.4 mm >doesn't exist< >doesn't exist<
Front axle
dimensioned sketch

Note: All lengths (A, C, E) ± 2 mm
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Length (value A) 225 mm 225 mm 225 mm 243 mm 242 mm 252 mm 244 mm 244 mm
Diameter 1 (value B) 20 mm 20 mm 20 mm 20 mm 20 mm 20 mm 20 mm 20 mm
Length diameter 1 (value C) 70.5 mm 70.5 mm 70.5 mm 80 mm 81 mm 82 mm 70 mm 70 mm
Diameter 2 (value D) 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm
Length diameter 2 (value E) 115 mm 115 mm 115 mm 134 mm 132 mm 138 mm 142 mm 142 mm
Thread (value F) Left-hand thread Left-hand thread Left-hand thread Left-hand thread,
from no. 227 407 right-hand thread M14x1.5 		right-hand thread M14x1.5 right-hand thread M14x1.5 right-hand thread M14x1.5 right-hand thread M14x1.5
Rear axle
dimensioned sketch

Note: All lengths (A, C, E) ± 2 mm
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Overall length (value A) 242 mm 242 mm 240 mm 338 mm 319,5 mm 322 mm 310 mm 310 mm
Design end 1 (value B) hexagon head WS
axial drillhole Ø 6 mm x 10 mm 		hexagon head WS
axial drillhole Ø 6 mm x 10 mm 		hexagon head WS
axial drillhole Ø 6 mm x 10 mm 		Ø 20 mm Ø 20 mm Ø 20 mm Ø 20 mm Ø 20 mm
Length end 1 (value C) 11 mm 11 mm 11 mm 128 mm 129 mm 132 mm 111 mm 111 mm
Diameter 2 (value D) 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm 17.0-0.05 mm
Length diameter 2 (value E) 210 mm 210 mm 210 mm 161 mm 162.5 mm 161 mm 170 mm 170 mm
Thread (value F) right-hand thread M14x1.5
left side 		right-hand thread M14x1.5
left side 		right-hand thread M14x1.5
left side 		right-hand thread M14x1.5 right-hand thread M14x1.5 right-hand thread M14x1.5 right-hand thread M14x1.5 right-hand thread M14x1.5
Wheels
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Wheel diameter 19" 19" 19" 19" 19" 18" 18" 18"
Rim drop centre rim 2½ x 19 drop centre rim 2½ x 19 drop centre rim 2½ x 19 drop centre rim 2½ x 19 drop centre rim 2½ x 19 drop centre rim 3 x 18 drop center rim 2.15B x 18 drop center rim 2.15B x 18
Rim material coated steel coated steel coated steel coated steel coated or chrome-plated steel buffed aluminium
coated steel version for
authorities' version or side car 		buffed aluminium
coated steel version for
authorities' version or side car 		silvergrey coated steel
(buffed aluminium or
chromed-plated steel
at extra charge)
Number of spokes 36 36 36 36 36 36 36 36
Tyres 3 x 19 3 x 19 3 x 19 3,25 x 19 3,25 x 19 3,25 x 18 3,25 x 18 3,25 x 18
Spokes
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Front wheel:
Dimensions
and numbers 		ED M3.5x170, ED M3.5x220
oder M4x173, M4x222
18 pieces each 		ED M3.5x170, ED M3.5x220
oder M4x173, M4x222
18 pieces each 		M3,5x165, M3,5x220
18 pieces each 		ED M3,5 X 154, ED M3,5 X 210
18 pieces each 		ED M3,5 X 154, ED M3,5 X 210
18 pieces each 		ED M3,5 X 140
36 pieces 		ED M3,5 X 140
36 pieces 		ED M3,5 X 140
36 pieces
Rear wheel:
Dimensions
and numbers 		ED M3.5x165, ED M3.5x220
oder M4x167, M4x220
18 pieces each 		ED M3.5x165, ED M3.5x220
oder M4x167, M4x220
18 pieces each 		M3,5x165, M3,5x220
18 pieces each 		ED M3,5 X 154, ED M3,5 X 210
18 pieces each 		ED M3,5 X 154, ED M3,5 X 210
18 pieces each 		ED M3,5 X 140
36 pieces 		ED M3,5 X 140
36 pieces 		ED M3,5 X 140
36 pieces
Form hooked hooked hooked straight straight straight straight straight
Colour black black black black zinc-plated chrome-plated chrome-plated chrome-plated
Hub
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Material steel steel steel steel steel aluminium aluminium aluminium
Brake drum half drum
front Ø 160 mm
rear 180 mm 		half drum
front Ø 160 mm
rear 180 mm 		half drum
front Ø 160 mm
rear 180 mm 		half drum
both Ø 160 mm 		half drum
both Ø 160 mm 		drum
both Ø 160 mm 		drum
both Ø 160 mm 		drum
both Ø 160 mm
Total number of spokes 36 36 36 36 36 36 36 36
Additional parts for
installation of spokes 		>not required< >not required< >not required< >not required< >not required< spoke adaptors spoke adaptors spoke adaptors
Additional parts for
installation of bearings 		>not required< >not required< >not required< >not required< >not required< steel bushing insert hub
(depending on bearings!) 		steel bushing insert hub steel bushing insert hub
Wheel bearing bush
dimensioned sketch

Notes:
cylindrical part Ø 47.7 mm,
total length 80 mm
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Bearing seats >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< stepped (ike 1),
316 833 with undercuts
at A and D (like 2) 		with undercuts
at A and D (like 2) 		with undercuts
at A and D (like 2)
Thread length M42x1.5 (value A) >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 10 mm,
316 833 12 mm (incl. undercut) 		12 mm (incl. undercut) 12 mm (incl. undercut)
End of seat outer bearing (value B) >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 27 mm,
316 833 25 mm 		25 mm 25 mm
Start of seat inner bearing (value C) >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 54 mm,
316 833 54 mm 		54 mm 54 mm
End of seat inner bearing (value D) >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 72 mm,
316 833 69 mm (incl. undercut) 		69 mm (incl. undercut) 69 mm (incl. undercut)
Undercut for spacer bushing (value E) >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< 74.5 mm,
316 833 74.5 mm 		74.5 mm 74.5 mm
Spacer tubes
Dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
I Spacer bushing >doesn't exist< >doesn't exist< >doesn't exist< ... >doesn't exist<
II Spacer tube xmb.enx xmb.enx xmb.enx xmb.enx xmb.enx
316 833 xmb.enx 		xmb.enx xmb.enx
III Shim >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist<
316 833 xmb.enx 		xmb.enx xmb.enx
Wheel bearings
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Wheel bearings front wheel 2x grooved ball bearing 6303 2x grooved ball bearing 6303 2x grooved ball bearing 6303 1x grooved ball bearing 6303,
1x angular contact bearing 3203x 		1x grooved ball bearing 6203,
1x angular contact bearing 3203 		1x needle bearing NKJHS 17A,
1x angular contact bearing 3203x,
316 833
2x taper roller bearing 30203 		2x taper roller bearing 30203 2x taper roller bearing 30203
Bearing seats in ... hub directly hub directly hub directly hub directly in hub itself steel bushing insert hub
(depending on bearings!) 		steel bushing insert hub steel bushing insert hub
Wheel bearings rear wheel 1x tumbler bearing 1303,
1x grooved ball bearing 6305 		1x tumbler bearing 1303,
1x grooved ball bearing 6305 		1x tumbler bearing 1303,
1x grooved ball bearing 6305 		1x grooved ball bearing 6303,
1x angular contact bearing 3203x 		1x grooved ball bearing 6203,
1x angular contact bearing 3203 		1x needle bearing NKJHS 17A,
1x angular contact bearing 3203x,
316 833
2x taper roller bearing 30203 		2x taper roller bearing 30203 2x taper roller bearing 30203
Bearing seats in ... bearing sleeve
cover rear axle gearbox 		bearing sleeve
cover rear axle gearbox 		bearing sleeve
cover rear axle gearbox 		hub directly hub directly steel bushing insert hub
(depending on bearings!) 		steel bushing insert hub steel bushing insert hub
Pressure bushings
Dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Left side (depending on hub cap)
diameter collar A x length B
orientation collar 		front wheel only

towards centre 		front wheel only

towards centre 		front wheel only

towards centre
outwards 		Ø 24 mm x 9 mm
towards centre 		Ø 24 mm x 9 mm
towards centre
313 225
Ø 36 mm x 10 mm
outwards 		Ø 36 mm x 10 mm
outwards 		Ø 36 mm x 10 mm
outwards
Right side ("brake side")
diameter collar A x length B
orientation collar 		front wheel only

towards centre 		front wheel only

towards centre 		front wheel only

towards centre
outwards 		Ø 24 mm x 9 mm
towards centre 		Ø 24 mm x 9 mm
towards centre 		Ø 24 mm x 9 mm
towards centre 		Ø 24 mm x 9 mm
towards centre
Wheel bearings fixation
Sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Front wheel bearing cap bearing cap bearing cap Seeger circlip retainer (like 1)
254 051 like 2
(self locking) 		retainer (like 2)
316 833 like 3
(depending on bearings!) 		retainer (like 3) retainer (like 3)
Rear wheel bearing cap
>doesn't exist< 		bearing cap
>doesn't exist< 		bearing cap
>doesn't exist< 		Seeger circlip retainer (like 1)
254 051 like 2
(self locking) 		retainer (like 2)
316 833 like 3
(depending on bearings!) 		retainer (like 3) retainer (like 3)
Hub caps
Sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Cross-section center >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< like 1
313 225 like 2
caution when refitting
several parts requ. 		like 2 like 2
Brakes general
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Brake design half drum brake
front Ø 160 mm
rear 180 mm 		half drum brake
front Ø 160 mm
rear 180 mm 		half drum brake
front Ø 160 mm
rear 180 mm 		half drum brake
both Ø 160 mm 		half drum brake
both Ø 160 mm 		drum brake
both Ø 160 mm 		drum brake
both Ø 160 mm 		drum brake
both Ø 160 mm
Brake lining dimensions front 20 x 170 mm,
rear 20 x 200 mm,
each 4 mm thick 		front 20 x 170 mm,
rear 20 x 200 mm,
each 4 mm thick 		20 x 190 mm,
3 mm thick 		25 x 170 mm,
4 mm thick 		25 x 170 mm,
4 mm thick 		35 x 170 mm,
4 mm thick 		35 x 170 mm,
4 mm thick 		35 x 170 mm,
4 mm thick
Riveting holes 5, each Ø 3.5 mm 5, each Ø 3.5 mm 5, each Ø 3 mm 7, each Ø 3 mm 7, each Ø 3 mm 8, each Ø 3 mm 8, each Ø 3 mm 8, each Ø 3 mm
Brake cam front
Sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Diameter x length
(without capping washer),
number of ring grooves 		Ø 12 mm x 63 mm,
3 		Ø 12 mm x 75 mm,
4 		Ø 12 mm x 75 mm,
4 		Ø 14 mm x 65 mm,
3 		Ø 14 mm x 65 mm,
3 		Ø 14 mm x 65 mm,
3
Connection with brake lever square peg 10 mm
ending with M8x1 bolt 		square peg 10 mm
ending with M8x1 bolt 		square peg 10 mm
ending with M8x1 bolt 		square peg 10 mm
ending with M8x1 bolt 		square peg 10 mm
ending with M8x1 bolt 		serrated shaft Ø 14 mm serrated shaft Ø 14 mm serrated shaft Ø 14 mm
Cam length 20 mm 20 mm 20 mm 25.5 mm 25.5 mm 25.5 mm 25.5 mm 25.5 mm
form capping washer like 1 like 1 like 1 like 1 like 1 like 2 like 2 like 2
Dimensions inner washer
outer diameter x
inner diameter x thickness 		>doesn't exist< >doesn't exist< >doesn't exist< Ø 26.5 mm x Ø 12.7 mm x1.0 mm Ø 26.5 mm x Ø 12.7 mm x1.0 mm Ø 25 mm x Ø 14 mm x1.2 mm Ø 25 mm x Ø 14 mm x1.2 mm Ø 25 mm x Ø 14 mm x1.2 mm
Brake lever front wheel
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Distance hole centres (total length) 65 mm (80 mm) 65 mm (80 mm) 65 mm (80 mm) 65 mm (80 mm) 65 mm (80 mm) 85 mm (106 mm) 85 mm (106 mm) 85 mm (106 mm)
Connection brake cam shaft square hole 10 mm square hole 10 mm square hole 10 mm square hole 10 mm square hole 10 mm Serrated hole Ø 14mm
with clamping 		Serrated hole Ø 14mm
with clamping 		Serrated hole Ø 14mm
with clamping
"Working end" Receptor for Bowden cable nipple Receptor for Bowden cable nipple Receptor for Bowden cable nipple Receptor for Bowden cable nipple Receptor for Bowden cable nipple Forked with 14 mm holes for
receiving adjuster 		Forked with 14 mm holes for
receiving adjuster 		Forked with 14 mm holes for
receiving adjuster
Adjustment screw
sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Design slotted full length
with latching groove 		slotted full length
with latching groove 		slotted full length
with latching groove 		slotted full length
with latching groove 		slotted full length
with latching groove 		slotted full length
with latching groove 		slotted full length
with latching groove 		slotted full length
with latching groove
Thread x total length M8 x 54 mm M8 x 54 mm M8 x 54 mm M8 x 54 mm M8 x 54 mm M8 x 54 mm M8 x 54 mm M8 x 54 mm
Brake pedal
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Distance bolt centre - front tip 160 mm 160 mm 270 mm 270 mm 270 mm 270 mm 270 mm
Design straight straight straight straight straight bending outwards from bolt
deviation 2 cm 		bending outwards from bolt
deviation 2 cm 		bending outwards from bolt
deviation 2 cm
Lever for brake rod part of lever (one piece)
fixed angle ca. 120 ° 		part of lever (one piece)
fixed angle ca. 120 ° 		part of lever (one piece)
fixed angle ca. 120 ° 		on inner bolt end
position adjustable via serration
note: tapered! 		on inner bolt end
position adjustable via serration
note: tapered! 		on inner bolt end
position adjustable via serration
note: tapered! 		part of lever (one piece)
fixed angle ca. 120 ° 		part of lever (one piece)
fixed angle ca. 120 °
Finish black coated black coated chrome-plated chrome-plated black coated black coated black coated
Block angle bracket mounted
between pedal and frame 		angle bracket mounted
between pedal and frame 		angle bracket mounted
between pedal and frame 		footpeg mounting point
of frame 		footpeg mounting point
of frame 		rubber of footpeg rubber of footpeg rubber of footpeg
Brake rod
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Total length
(without wing nut) 		63 cm 63 cm 52.5 cm 52.5 cm 53.5 cm 54 cm 54 cm
Split pin at forked head rear end, bike side
 rear end, bike side
 rear end, bike side
 front end, centered
right through small lever 		front end, centered
right through small lever 		front end, centered
right through small lever 		front end, bike side
 front end, bike side
Connection brake light switch >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< >doesn't exist< with ear next to fork head M6x25 threaded bolt
at brake pedal 		M6x25 threaded bolt
at brake pedal
Brake cam rear
Sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Diameter x length
(without capping washer) 		Ø 12 mm x 117 mm Ø 12 mm x 117 mm Ø 12 mm x 117 mm Ø 12 mm x 124 mm Ø 12 mm x 124 mm Ø 14 mm x 129 mm Ø 14 mm x 148 mm Ø 14 mm x 148 mm
Connection with brake lever serrated shaft Ø 12 mm
ending with M8x1 bolt 		serrated shaft Ø 12 mm
ending with M8x1 bolt 		serrated shaft Ø 12 mm
ending with M8x1 bolt 		serrated shaft Ø 12 mm
ending with M8x1 bolt 		serrated shaft Ø 12 mm
ending with M8x1 bolt 		serrated shaft Ø 14 mm
ending with M10x1 bolt 		serrated shaft Ø 14 mm
ending with M10x1 bolt 		serrated shaft Ø 14 mm
ending with M10x1 bolt
Cam length 20 mm 20 mm 20 mm 25.5 mm 25.5 mm 25.5 mm 25.5 mm 25.5 mm
form capping washer like 1 like 1 like 1 like 1 like 1 like 2 like 2 like 2
Dimensions inner washer
outer diameter x
inner diameter x thickness 		>doesn't exist< >doesn't exist< >doesn't exist< Ø 26.5 mm x Ø 12.7 mm x1.0 mm Ø 26.5 mm x Ø 12.7 mm x1.0 mm Ø 25 mm x Ø 14 mm x1.2 mm Ø 25 mm x Ø 14 mm x1.2 mm Ø 25 mm x Ø 14 mm x1.2 mm
Brake lever rear wheel
dimensioned sketch
R20 R23 R24 R25(/1) R25/2 R25/3 R26 R27
Distance hole centres (value A) 72 mm 72 mm 72 mm 65 mm 65 mm 65 mm
from no. 295 201 45 mm 		75 mm 75 mm
Total length (value B) 92 mm 92 mm 92 mm 87 mm 87 mm 90 mm
from no. 295 201 70 mm 		98 mm 98 mm
Connection brake cam shaft serrated hole Ø 12 mm serrated hole Ø 12 mm serrated hole Ø 12 mm serrated hole Ø 12 mm serrated hole Ø 12 mm serrated hole Ø 14mm serrated hole Ø 14mm serrated hole Ø 14mm
"Working end" Hole receiving
clevis pin 		Hole receiving
clevis pin 		Hole receiving
clevis pin 		Forked with 14 mm holes for
receiving adjuster 		Forked with 14 mm holes for
receiving adjuster 		Forked with 14 mm holes for
receiving adjuster 		Forked with 14 mm holes for
receiving adjuster 		Forked with 14 mm holes for
receiving adjuster
deviation angle α 0 ° 0 ° 0 ° 10 ° 10 ° 15 ° 30 ° 30 °
Adjuster rear wheel brake at ... brake pedal brake pedal brake pedal brake lever at rear wheel brake lever at rear wheel brake lever at rear wheel brake lever at rear wheel brake lever at rear wheel

Creative Commons License
This work is licenced under a Creative Commons Licence.

As of 08/05/2025

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