Capacitor testing

The correct functioning of a capacitor can be measured with (for example) a FLUKE multimeter. The value specified by the manufacturer is 0.22 μF (microfarad). Over time, a capacitor’s performance can be expected to decline. The left photo shows a broken capacitor: the measured value is 0.131 nF (nanofarad) = 0.000131 μF The right photo shows a properly functioning capacitor: the measured value is 0.249 μF. This is 13% higher than the specified value, but this does not affect proper operation. The value specified by the manufacturer is a chosen ideal value for the expected average engine rpm. This value is therefore
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Bearing radial play specifications

The table below shows the radial clearance specifications for all bearings used on the R24 – R69S models

Tools for disassembling & rebuilding R51/3 – R68 and R50 – R69S engines

A comprehensive list of special and generic tools

Pistons aren’t round

It’s a wide spread misconception that pistons must be round / cylindrical. The opposite is true, This is a new Kolbenschmidt R27 piston 68.50 mm:               From the Internet: Profile: If you roll a piston across a flat surface, you’ll notice it doesn’t roll in a straight line. This characteristic is called profile. Aluminum conducts heat significantly, so pistons are designed with a taper. The top of the piston (near the crown) has a smaller diameter than the bottom (near the skirt). The skirt itself is shaped like a barrel. This taper allows the
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Denfeld vs Pagusa saddle

The only difference between the Denfeld en Pagusa saddle is the saddle deck. There are small differences between the saddle deck frames: the shape of the frame and the front threaded bolt. The Pagusa saddle bolt it is a bit longer and has a spacer so that the front of the saddle deck sits +- 1.5 cm higher compared to the Denfeld saddle deck. The grain texture of the Denfeld rubber saddle deck surface is finer than the Pagusa grain texture. There is no quality difference All other parts are the same: subframe, Z-bracket, rubber spring, spring stop piece, mounting
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Light and horn switch, left side – quality issue

The Light & Horn Switch with P/N  61 31 8 048 162 does not properly fit on the Clutch Lever Assembly with P/N 32 72 2 072 112 The cause of this problem is clarified in the photos below. The ends of the switch housing extend too far into the clutch lever assembly. As soon as both parts are mounted together on the handlebar, the switch housing is pushed outwards, so that the switch housing can no longer be hooked behind the cam.  

R51/3 – R69S engine gear set dimensions

Based on a sample of 74 gear sets, this graph shows the frequency of the different gear sets and the spread around the target dimension of +0.

List of bearings in the 1 & 2 cylinder engine, gearbox and final drive

  Click thumbnail to open the list. R24 – R27           R51/3 – R68           R50 – R69S            

Gearbox cam plate comparison

Comparison of the different gearbox cam plates used in the R24 – R27 and R50 – R69S models. For more information about the R50 – R69S shifting system, click following links: Smooth shifting R50 – R69S R50 – R69S Old and New style shifter mechanism  

Upper valve spring cap 11 34 0 026 180

There are 2 versions of this spring cap available in the market. The top one is correct. The valve in the lower black spring cap is too deep, with the result that the force exerted by the valve spring is slightly less.                                              

Bearing cover R51/3 – R67/2, R50, R60

The front main crankshaft bearing is enclosed in the bearing bushing (P/N 11 11 0 002 156) by the front main bearing flange cover (P/N 11 11 0 002 176) and a spacer ring (P/N 11 21 0 016 244), to prevent axial movement of the crankshaft. If you notice that the 6207 bearing still has some movement in the bushing, it is usually caused by a worn main bearing flange: the edge of the flange has bent back over the years and therefore no longer has enough height (+- 4 mm) to enclose the bearing. With the correct pressing tool, the
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Wiring – ignition switch plate

Switch plate with P/N 61 32 8 048 173

Gearbox problems: shafts do not turn smoothly after assembly.

This is specifically aimed at 1 cylinder and /2 gearboxes. If you’ve tried everything and you can’t figure why the gearbox shafts do not turn freely, you can use following very time consuming method  🙂 to determine the cause: Instead of putting all 3 shafts in at the same time, put in 1 shaft at the time. Remove the input shaft seal from the gearbox: the seal makes it harder to rotate the input shaft, making it difficult to assess whether the shaft is running freely. Remove the idler gear and kickstarter gear segment. Whenever you install (and remove) one
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Cleaning of rubber parts

Some rubber parts are still provided with a (wax) layer when shipped: a mold release agent. A cleaning solution with hot dish soap and water is enough to remove this layer. Use rubbing alcohol for stubborn stickiness. Although alcohol is an effective cleaner for most kinds of stickiness, you should only use this cleaning agent on rubber occasionally. Dampen a clean rag with alcohol and wipe at sticky areas until they are removed. Rinse the rubber with water afterwards. Exposing rubber too often or too long to alcohol may cause it to break down more quickly than normal.

BMW motorcycle wheel bearings, 1956 through 1969 by Duane Ausherman

Very informative and comprehensive treatise on the tapered wheel bearings. Click on the photo to go to the relevant webpage:    

Seal material property comparison

A “strenght & weakness” overview of the different seal materials available in the market.

Diagnosing clicking sounds as a worn carburetor slide – by Scottie’s Workshop

Very informative video!    

Oil slinger screw

The oil slinger screws are not available from BMW anymore. Most suppliers now offer a general purpose DIN 963 M6 x 10 screw. However, the head of this screw is higher than that of the original screw: the head of the screw protrudes above the oil slinger surface. This may be undesirable in some cases. We now supply oil slinger screws with the same dimensions as the original screw.

Hardy disk installation R26, R27

To ensure the longevity and optimal operation of the Hardy disk, the distance between the output shaft flange and the drive shaft flange must be set at 30 mm + 1.5 mm

R68 Flywheel with /2 design

In the original R68 parts list (1953) the flywheel is shown in the exploded view of the same model as the R51/3 – R67/3 flywheels. (the ignition timing marks are different though) R68 flywheels also appear to have been made with the design of the later /2 models. I assume that these flywheels were a precursor in the transition to the R69.                    

Spherical and cylindrical rollers for connecting rods

The BMW specification for the radial clearance of the conrod big end & crankpin is based on the use of slightly spherical rollers in some of the crankshafts. The use of spherical rollers prevents the rollers from “biting” when the crankshaft flexes at high RPM. Today the new FAG Dürkopp conrod sets are equipped with cylindrical rollers. This requires a slightly larger radial clearance to prevent the rollers from getting stuck when the crankshaft flexes at high RPM. Spherical rollers (used) are identified by the wear track in the center of the roller:                
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Ignition keys

These photos show the difference between the Noris keys and the replica keys. This can help to identify the cause of malfunctioning ignition switch.      


All standard bearings we supply, are either from FAG or SKF. FAG is a brand of Schaeffler Group Germany. SKF is a Swedish company. Both companies have factories in different locations around the world. The country of origin is stated on the packaging. These can be countries like Portugal, Slovakia, USA, Republic of South Korea, India or China. We regularly have to explain that “made in China” is not a parallel import of Chinese brand bearings.               We purchase our bearings from ABF Bearings. ABF Bearings is a major worldwide ISO certified distributor of
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Valve adjustment problems – cylinder head sleeve height

If the valve adjusting screws have reached their end and there is still insufficient valve clearance, the cause may be (a combination of): the valves sit too deep in the valve seats the cylinder head sleeves have sunk deeper into the cylinder head over time. In our experience, the sleeves at the exhaust side sit usually deeper than at the intake side. Below an example of 2 R27 cylinder heads. The RHS sleeve at the intake side of cylinder head 1 has a height of 88.47 mm The LHS sleeve at the exhaust side of cylinder head 2 has a
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Phased out stock & damaged parts at reduced prices

PHASED OUT STOCK (undamaged): Prices are per 1 piece and ex VAT, click on part description to go to the web shop 2 x Membrane for 32 mm carburetor (Bing 165-810) – original Bing From €23.65 for €16.55 2 x Type identification emblem R90S on engine top cover – original From €50.86 for €35.60 2 x Valve seat ring intake 36.64 x 28.57 x 7.95 mm Kolbenschmidt From €17.10 for €11.95 2 x Valve seat ring intake 37.03 x 27.9 x 9.00 mm Kolbenschmidt From €17.10 for €11.95 1 x set Ferodo Platinum brakepads FDB108P > 1981 From €26.- for €10.- 8 x Cork seal for push rod tubes
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The UPS dilemma

The UPS dilemma Courier companies, such as UPS, DHL and Fedex, determine the price for sending packages based on the package weight or the package volume (volumetric weight). The highest number is used to calculate the shipping costs. To determine the volumetric weight, the dimensions (in cm) are multiplied and divided by 5000 For example: 1) package weight: 10 kgs package dimensions: 40 x 40 x 20 cm  – volumetric weight = (40 x 40 x 20) / 5000 = 6.4 kg In this case, the actual package weight of 10 kgs determines the shipping costs 2) package weight: 10
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Tools for R50 – R69 gearbox rebuild

We are regularly asked for a list of tools that are needed for a complete overhaul of the gearbox. Below an overview of the special Matra tools and some of the standard tools that are required / recommended for a succesful gearbox rebuild:   Most important “tool” is a good manual: Barrington manual:   BMW Factory manual – can be downloaded here:   NB0017 – Gearbox holder for vise                 M494/2 – socket wrench M14 for nut on output shaft (R50, R60) M494/2/1 – socket wrench M16 for nut on output shaft (R50/2
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New cylinder heads R51/3 – R60/2

Our price of these cylinder heads is higher than the price of other suppliers, for the following good reasons: 1. The valve guides are checked and reamed if needed. Some guides require upto 0.02 mm reaming.  Without these adjustments, the valves would get stuck quickly. 2. We replace the supplied non-rotating valves with rotating valves. 3. The cylinder head mating surfaces are flattened in case of visible/palpable edges in the mating plane or “curved” surfaces. The depth of the mating surface is measured, to make sure that the height of the collar on the cylinder does not exceed the depth
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2 cylinder crankshaft identification

Flow chart to identify a 2 cylinder crankshaft. Click on the flow chart and table for larger images, click <- arrow in your browser to return to this page.                                                            

Parts list – conversion from 6V to 12V for R51/3 – R68, R50 – R69S

This list shows the part numbers for all parts that need to be changed in case of a conversion to 12V  

Disassembly of an R27 engine

This video shows the disassembly of an R27 engine, including some basic measurements of the crankshaft. Click this image to watch the video on Youtube:                        

Spark Plugs

Click image for table    

Turn signal switch & switch support

Turn signal switch with P/N61318048152AM will only fit with switch support with P/N32722072175. The original Magura switch support is too high, so the switch does not connect properly to the switch support. This leaves an opening visible.                              

Repair of idle mix screw thread

This video shows the repair of the idle mix thread: a thin alu-bronze bush of M8 / M7 x 0.75 is installed in the carburettor, realizing a very wear-resistant and strong thread Click this image to watch the video on Youtube:  

Removal and installation of tappet guide bushings

In this video a method is shown to remove the old and install new tappet guide bushings from a 2 cylinder engine. The new bushings with an outer diameter of 24.97 mm have an interference fit with the crankcase. After installation, the bushings ID needs to be reamed / honed to give a tappet clearance of 0.02 – 0.04 mm Click this image to watch the video on Youtube:                    

Crown and pinion gear contact pattern

Staburag is a good alternative for “Prussian Blue” when determining the contact pattern between the crown and pinion gears. By adding a few lines, the contact pattern becomes even easier to read.                  

Flywheel R69

The R69 flywheel differs from the other / 2 flywheels because of the position of the ignition marks:

Wiring diagram R51/2, with brake light – in colour

Contributed by Matthias and Erich Lemmerer Click here for PDF file: Stromlaufplan 51_2 mit Bremslicht

Wiring diagram R51/2, without brake light – in colour

Contributed by Matthias and Erich Lemmerer Click here for PDF file: Stromlaufplan 51/2 ohne Bremslicht

Wiring diagram R51/3 – R68, without brake light – in colour

Contributed by Matthias and Erich Lemmerer Click here for PDF file: Stromlaufplan R51 R67 R68 1951_52 V01_21  

Wiring diagram R51/3 – R68, with brake light – in colour

Contributed by Matthias and Erich Lemmerer Click for PDF file: Stromlaufplan R51 R67 R68 1953_54 V01_21

Smooth shifting R50 – R69S

A comparison of the required shifting force needed, between the old and new style shifting mechanism.                                                                                      

Restoration of our 1975 BMW 2002 automatic

By Lusso Classics, Hilversum, The Netherlands

BMW /2 Swing arm leaks – final drive leaks by Scottie Sharp

Link to the original post: BMW /2 Swing arm leaks, final drive leaks During a routine oil change, it was noted that the drive shaft housing was empty.   Could it have been stolen by vagrants?   A guy works hard for his oil just to have vagrants come and steal it. Well, before contemplating a move to a safer neighborhood, BMW riders should remember that oil migration from the drive shaft housing to the rear drive is a common problem. There are three ways that oil can migrate from the driveshaft housing to the final drive and they
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Removing and reinstalling the drive shaft flange

The drive shaft flange has a press fit with the shaft. A workshop press is needed to press the flange off and onto the shaft. When removing the flange, standard press plates can be used to support the flange. However, to press the flange back on, the drive shaft collar must be supported. There are several ways to do this, but this tool works best for us. The tapered shape of the 2 halves and the ring ensures that the shaft is increasingly clamped during pressing. The edge of the hole between the 2 halves follows the radius of the
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Exhaust pipes comparison R25, R25/2, R26, R27

Without direct comparison, it can be difficult to distinguish the difference between the R25-R25/2, R26 and R27 exhaust pipes. This photo shows how you can easily determine the type of exhaust pipe:   The R25, R25/2 exhaust pipe is significantly longer at the straight end than the R26 exhaust pipe:

R51/3 – R68 Throttle assembly – sliding block design

For unknown reasons, the supplier of the after-market throttle assemblies for the R51/3 – R68 models (pn 32722072350), has decided the modify the design of the sliding block. The old sliding block used to have recesses to hold the cable ends, the new version does not. While in the new version the cables cannot “escape” either, the cable ends can rub against the inside of the throttle body causing unwanted wear. We therefore remove the new sliding block from the throttle assembly and add the correctly designed older sliding block. This however increases the price of the throttle assembly.  
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Comparison R60 and R60/2 pistons

Piston for R60 with 130 mm conrod and R60/2 with 125 mm conrod  

Old dirty R69 – from basket to bike

  Click this link for the full story:                        

Testing valve springs

Valve springs can lose a lot of their strength over the years, as seen with this R25/3 valve spring: a new spring measures 16.6 kg, the old spring 10.1 kg, almost 40% lower. Lower spring tension usually causes no or minor problems on low revving engines, but it can lead to loss of power / misfiring on higher revving engines as a result of valve float                 The test device:  

R50 – R69S Old and New style shifter mechanism

Comparison between the “old” and “new” version of the R50 – R69S shifter mechanism. Click following link for a comparison of the cam plates: Gearbox cam plate comparison

Fitting the correct distribution gear set

The number stamped in the crankcase (from -10 to +10) refers to the size of the crankshaft and camshaft gears installed by the BMW factory. After 60 – 70 years of service, the crankcase may have grown, which means that the original gear set may not be the optimal set anymore (0.01 to 0.02 mm play between the 2 gears). One way to determine the correct gear set number is to measure the c-t-c distance between the crankshaft and camshaft. This value must then be compared to the nominal c-t-c distance. This is impossible without very accurate measuring tools. The difference in
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List of fasteners R50 – R69S

A comprehensive list of bolts, nuts and washers for the R50 – R69S models Click image for list :                          

Valve seat inserts (Dura-Bond)

Recommended press fitting for valve seat inserts in aluminum cylinder heads: OD insert 30 – 40 mm: 0.15 mm / 0.0059″ OD insert 40 – 50 mm: 0.18 mm / 0.0071″   Spindle speed for cutting a seat pocket in aluminum cylinder heads: 400 – 600 rpm It’s recommended NOT to freeze (f.i. with liquid nitrogen) the sintered valve seat inserts before installation. The valve seats are to be pressed in with a flat and square seat driver tool. The valve seat is inserted with the radius side down.   Source: DuraBond

BMW motorcycles in the Netherlands

The information below comes from the Dutch RDW database (= Dept. of Motor Vehicles) In the Netherlands, there are at least 164 registered BMW motorcycles from the (pre-)war era and at least 3,225 registered BMW motorcycles from the 1948 – 1969 era – 3.225 motorcycles makes +- 1.2% of all R24 – R69US motorcycles built by BMW – of these 3,225 motorcycles,  almost half (48%) are /2 models (R50 – R69US) – 36% of these motorcycles is 25 years or more with the current owner, longest period is 58 years (situation 2019) – about 10 of these motorcycles have only
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Installing atomizer in Bing Carburetor

By Richard Sheckler, Wayne, Ohio A tool that can be used to accurately and squarely install and press fit the atomizer in place without damage. The replacement part has a different size knurling than the original, and therefore has sufficient resistance to remain in place for a long time.    


Some statistics based on last 5 years (2013 – 2018)      

Wiring diagram R51/2

BMW R51-2 Wiring diagram B&W  (click for larger image)    

Side stands for EU and USA models

There is a clear length difference between the side stands for the R50 – R69S models and the R50US, R60US and R69US models (due to different configurations of the front fork) These are therefore not interchangeable.

Puller spindles and lubricants

All Matra tools with spindles such as M355, M499 / 1/2, M422a, M501 and M282 work much better (more smoothly) if a small amount of lubricant (eg Molykote G-n Metal Assembly Paste) is applied to the thread. This prevents galling of the thread under heavy load and reduces, to a certain extent, unwanted rotation of the other part of the tool.

Installation instructions 12V dynamo system VAPE

Click here for installation instructions 12V dynamo system VAPE: Dynamo System 70 80 499 0XX

1 and 2 pin Breather plates

If you are working on the overhaul of a 2 cylinder engine block with the old 1 or 2 pin breather plate, it is advisable to replace it with the later version with cast-in pins The pins of the early 1 or 2 pin breather plates are known for loosening or breaking off, causing damage to gear case cover. However, this means that the complete set of gears must be replaced (from 20° to 30° gears) The breather plate of the newer version is also available with larger slots, reducing pressure in the engine block during the downward movement of
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Rim width

The width of rims can be measured in 2 different ways: the inside or the outside. This means that one and the same rim can be indicated both in (for example) 2.15 “and 3.08″ WM2: inside 1.85″ (47 mm) outside 2.72″ (69 mm) WM3: inside 2.15″ (55 mm) outside 3.08” (78.2 mm)      

Timing gear numbers

For the correct set, check the number marked in the crankcase. The number is found near the upper engine mount, see following examples: In some cases, when the engine has had a long service life, it may need a different gear set number to get the required 0.02 mm clearance. However, this can only be determined through an accurate measurement.   The 30° gear set can be used to replace the 20° gear set on all 1950 to 1963 models. This requires following additional parts: › part nr. 11410052156 – oilpump gear 30° Only for crankshaft with 17 mm taper: › part nr. 11310016400 – 1.5
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BMW posters

These posters are only shown for information. We do not sell these posters. We welcome BMW posters from the pre-69 era.  Mail us at    

Mono and Twin throttle assemblies

The R50 – R69S dual cable throttle assembly cannot be simply converted to a R26, R27 single cable throttle assembly by replacing the cam & chain and the cover. The depth of the recess in single cable cam and dual cable cams differs. The mono cam will not sit deep enough to engage with the throttle twist grip. Vice versa: the dual cable cam will not fit in the single throttle cable assembly: it’s too high.

Leaking carburetors

A frequently asked question is how to fix a leakage of the idle mixing screw. Further tightening the nut of the idle mix screw is certainly not the solution: holes have been drilled in the idle mix screw which connects the idle mix chamber to the the outside air. If fuel leaks out through the same bore, it simply means that the fuel level in the float bowl is too high. (assuming that the bike is on the center stand, if the motorcycle is placed on the side stand, there is a greater risk of leakage) If the carbs keep leaking, it’s
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Crankcase surface repair

By Michel Loos, The Netherlands The photos are self-explanatory. Steps:  filing  – sanding – pneumatic hammer – aluminum oxide blasting (Edelkorund) – glass bead blasting  

Sound of open mufflers on a BMW R51/3

Just can’t get enough of the sound of open mufflers

Instructions for Cylinder black (Einbrennlack)

Cylinder black with part nr. 09122 For temperatures up to 500 °C continuous use and up to 700 °C with impact load 200 ml is sufficient for 2 to 3 large cylinders. Ideal for spraying and painting engine cylinders, exhaust systems and other metal objects subject to high heat. Classic cylinder lacquer is initially thermoplastic; in other words although it is air-drying, it becomes sticky even with moderate heat, expands and hardens again when it cools down. This process is repeated as long as the polymerization temperature is not reached. The lacquer must be heated at least once to 150-180 °C to finally cure. After
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Solving hard-start problems by Craig Vechorik

  Click this link:   In addition: The resistance across the two spark plug leads on the ignition coil is usually 11 – 12 K Ohm (original coils and new “made in Germany” coils). Some after-market coils have a resistance up to 20 K Ohm. When the magnetic field of the rotor is still OK, this higher resistance will not necessarily cause a problem. A weak spark at the spark plug can have different causes: a broken or poor quality ignition coil is one of them. When the insulation (schellac) within the coil is damaged (crazing), the internal windings will short circuit,
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Replacement for Matra 513 tool – rear swing arm pivot pins

The rear suspension pivot pins of the R26, R27 and R50 – R69S models can be adjusted with the use of the Matra 513 tool. However, no replicas are made of the Matra 513 tool. The alternative is a pin wrench such as PN 31421234399.W (Pin wrench for front fork cap screw R69US, R50/5 – R100) Although the diameter of the pins is just under 4 mm and the holes in the pivot pins are 5 mm, this tool functions well. The alternative is pin wrench 31422000243.W (Pin wrench for front fork cap screw R25/3): the pins have a diameter of just
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R27 Throttle assembly switches

3 types of throttle assembly/switch combinations were used on the R27 models 1. From nr. 372001 Turn signal switch & headlight flasher with PN61318048152 and switch mount with PN32722072175                 2. From nr. 379795 Dip switch (abblendschalter) with PN61318048182 and switch mount with PN32722072180                         3. From nr. 385265 Turn signal switch with PN61318048183 (horn contact) and switch mount with PN32721230878 (old PN32722072181) (sloping)                             Other parts for a
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Repair part for R51/3 – R68 half hub wheels

We now offer a top quality wheel hub repair part (PN 36312030026.7) for the R51/3 to R68 half hub wheels – splines have a perfect slide fit with the original BMW driving dog (PN 33120026232) – the HRC value of the repair part is between 30 to 34, measured at the splines. An original wheel hub measured 29 HRC – the repair part has the appropriate alternating recesses for the spokes, both on the front and back side of the flange:    the recess for the spoke head is deeper and has a concave shape, whereas the recess for the spoke bend
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Dimmer switch R25, R51/2

There are 2 versions available in the market. The one on the right has a lower push button housing. The hole in the housing does not align with the hole in the connector, as a result the wire cannot be connected properly.

Zylinderköpfe Übersicht 500 / 600 ccm

Overview of the different types of cylinder heads used on the R51/2 – R68 and 50 – R69S models Click here to view and dowload PDF file   Contributed by Erich and Matthias Lemmerer

BING jets

BING jets are stamped with numbers, such as 35, 40 (idle jets) and 110, 115, 120 etc (main jets). One would expect that these numbers refer to the diameter of the jet bore, however this is not the case. This is confimed by the company BING in Germany. A few examples of main jets measured with a wire / jet gauge: BING 44-051 main jet 130 = gauge 120 (= 1.2 mm) main jet 125 = gauge 110 (= 1.1 mm) main jet 120 = gauge 105 (= 1.05 mm) main jet 110 = gauge 95 (=0.95 mm)            
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BMW R51/2 Test (German)

Courtesy of Erich & Matthias Lemmerer, Austria

Carburetor flanges

The Bing carburetors used on the R51/3 to R69S models came with 3 different flanges. We sometimes get the question: can I put carburetor X on BMW model Y? In theory you can put an R51/3 carburetor on a R69 engine and even get the engine running, but you will quickly discover that the air pipes won’t fit. These images are self explanatory   Modified carburetors can be found in the market that fit the R68, R69 and R69S cylinder heads. However, there are some differences from the original models, most notably the carburetor flange:              
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Matra 282 tool

We mill 2 planes on the threaded bushing so that it is possible to use a 22 mm wrench on the threaded bushing. This is necessary in cases where (for instance) the crankshaft bearing is glued to the bearing journal, to prevent the threaded bushing from rotating while tightening the central bolt

Foot brake lever pin repair

By Richard Sheckler, Wayne, Ohio These pins wear out over the years for lack of lubrication, design and abrasives from the road working their way into the mating surfaces. Some early axis pins came equipped with a pre-drilled grease passage and a grease nipple. The procedure for repair can be replacement with a new pin available from Bench Mark Works or one of the outlets in Europe. For those who have access to a lathe and have the time and materials to make the repair and upgrade, please note the following: First step is to remove the axis pin from
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Reparatur Anleitung R51/2 (German)

. Click here to view and download PDF file     Contributed by Matthias and Erich Lemmerer . . . . . . . .

Wiring diagram R25

Stromlaufplan BMW R25

Wiring diagram R25/2

Stromlaufplan BMW R25/2

R20 front fork

By Richard Sheckler, Wayne, Ohio. ……….. the original inner shafts were so badly worn, they could not be saved, so I replaced the center section of each tube with chrome moly seamless tubing by first machining each end to fit inside the new counter bored chrome moly steel tubing, then silver brazed in place. After they cooled, put them on the lathe between centers and machined and polished to size. The bushings inside the outer fork tubes were made from oil-lite bronze.  

R51/3 & R67 engine numbers

In the course of 1951, BMW changed the format of the engine number and the BMW letters cast in the engine case. The upper one is the old format. Note the dots between the BMW letters. The early engine cases had the VIN number stamped in an oval window. Later on the VIN number moved to the area just above the pushrod tubes Photos: Manolis Saravelakis, Greece                                                            

Motorcycle Service and Restorations Manuals

We offer the restorations manuals from Barrington Motor Works for following models (click the link): R26 – R27 R51/3 – R68  R50 – R69S   A copy of the original BMW Repair Manual R50, R60 and R69S can be downloaded here: Download            

Cylinder heads R50 – R69S: butterheads and LK heads

Very informatieve article by Duane Ausherman on “butterheads” and LK heads:

Checking R27 oil pump

A simple tool to check the working of an R27 oil pump, without starting the engine by G.M. de Kok, The Netherlands Will also work on other mono BMW’s Silver steel rod 8 mm x 22 cm, diameter of square part = 7 mm

Breather plates on the R51/3 – R69S engines

3 different breather plates have been used on the boxer engines:

Brake levers with finger grooves

The brake levers with finger grooves (PN32722072252) currently available in the market, do not fit in the throttle housing of the R26, R27, R50 – R69S models. The hole for the lever screw is of few thenth of a millimeter off it’s original position: the lever gets blocked and cannot be “opened”. New brake levers that do not have this problem are only expected to become available by the end of 2017. Till then, the solution is to mill off +- 0.3 mm from the edges on both sides. After polishing, no traces of milling are visible anymore. This is what
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Exhaust pipes

Different exhaust pipes are available in the market, unfortunately not always an exact replica of the original pipes: the shape of the bends does not correspond with the original BMW exhaust pipes as can be seen on this picture. The 2 lower exhaust pipes are identical to the original pipes.   Next to that, these pipes follow a slightly different path than the original exhaust pipes. This causes a problem for the R67 – R67/3 models: in the horizontal section, they’re not running close enough to the frame, causing too little clearance between the brake pedal and the right-hand exhaust pipe,
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Exhaust systems R50 – R69S

Table with part numbers Click here to view a larger table  

Transmission upgrade/rebuild to “S” gearbox ratios

This modification and upgrade, using BMW components, results in a lower-ratio gearing for R26, R27, R50 and R60 gearboxes producing smoother, robust and responsive performance especially in 1st, 2nd and 3rd gear changes while 4th gear is unchanged. The “S” gear ratios allow the rider to accelerate smoothly through gear changes by letting the motor rev freely through an optimum power-torque range. Although the 3rd gear of both gearboxes have the same number of teeth, they are different: The standard gear has a diameter of 65.6 mm and the S-type gear has a diameter of 65.2 mm. They have a
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R50S & R69S emblems

Different qualities emblems are found in the market. See this example of the R50S emblem. In our opinion, the upper one is the better quality, both in shape and in finishing.   The differences are easily recognized: for example the shape of the “5” and “S”   The upper emblem follows the contour of the rear fender, the lower one is too flat. The back side of the lower emblem doesn’t have the smooth finish of the upper one. Please note that these emblems are very fragile! During installation, make sure that the holes in the rear fender are exactly
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BING inserts (Mischkammer Einsatz)

Overview of the different inserts used in Bing carburetors

Crankshaft shims

Overview of the different crankshaft shims used in the boxer engines

Carburetor reconditioning

With hardly any new carburetors being produced by BING for the < 1969 BMW mono and twin motorcycles, it’s getting increasingly important to be able to repair and recondition the used original carburetors. Luckily, special parts and tools are available nowadays to restore the carburetors to a good working condition. A. Idle mix screw: very often, the M7 x 0.75 mm screw thread in the carburetor housing is worn out. There are 2 good solutions to this problem. 1. drill the threaded hole to 7.2 mm – cut M8 x 0.75 mm screw thread – install the idle mix screw with
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Repair manual R50, R60, R69S (DE, EN, FR, ES)

A printed copy can be ordered here: Free download here: Page 1-43          Technical data Page 44-59        Removal of power train Page 60-89        Engine  Page 90-101      Transmission Page 102-109     Final drive Page 110-123     Wheels, brakes and forks Page 124-149     Electrical equipment Page 150-157     Sidecar mounting Page 158-160    Wiring diagram    

Pin striping on R26, R27 and R50 – R69S

The official pinstripe layout by BMW is as follows: Wide line: 5mm Narrow line: 1,5mm Distance between the two lines: 4mm   In the Barrington R26, R27 manual, following guidelines are given (measured on original fenders): – The setback of the wide stripe from the fender edge on many front and rear fenders is relatively constant at approx. 8.2 – 8.4 mm. – The wide stripes on 4 original fenders measured from 4.5 to 4.7 mm on one fender and 4.7 to 6 mm on another. – The gap between the 2 stripes on 2 rear fenders varied from 4.5 to
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Driving dog R51/2 – R68

Part nr: 33120026232 Next to the original BMW driving dog, an after-market version is available in the market. At first view, the after-market product gives the impression of high quality machining. However, there are at least 2 flaws: 1. the geometry of the splines:the splines of the after-market part almost have a V shape instead of the trapezium shape on the original part. This V-shape is normally seen on worn splines 2. The diameter of the needle bearing seat measures 39.94 mm whereas the original parts measures 39.97 mm. This will result in too much play on the needle bearing The
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Installation voltage regulator (Kleiber)

electronic-voltage-regulator-bmw-r24-r26-eng electronic-valtage-regulator-bmw-r51-3-r69s-eng electronic-voltage-regulator-bmw-r27-r50-eng

Installation of piston rings (KS)

By MS Motor Service (Kolbenschmidt) Click here to open as PDF: KS Installation of piston rings


Fair calender Oldtimer & Youngtimer: (mainly Germany) BMW forum:  (Deutsch)  (French)   BMW clubs Germany:   BMW clubs United States:   BMW clubs United Kingdom:   BMW clubs The Netherlands:   BMW clubs Denmark:   BMW clubs Indonesia:   Facebook: (that’s us)   (Vintage & Classic BMW Motorcycles USA)  (Richard Sheckler) (Scottie Sharpe)   Information sites: (R25/2 restoration- Deutsch) (/5 info – French)  (Survey of Chassis Numbers) (after-market hubs) (Gläser fairing – Deutsch) 
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Piston & cylinder tolerances

Piston and cylinder clearances for BMW R50, R60 and R69S (also valid for R50S and R69)


Source: Wikipedia The Lead Acid battery is made up of plates, lead, and lead oxide (various other elements are used to change density, hardness, porosity, etc.) with a 35% sulfuric acid and 65% water solution. This solution is called electrolyte, which causes a chemical reaction that produce electrons. When you test a battery with a hydrometer, you are measuring the amount of sulfuric acid in the electrolyte. If your reading is low, that means the chemistry that makes electrons is lacking. So where did the sulfur go? It is resting on the battery plates and when you recharge the
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Fuel tank repair

By Richard Sheckler, Wayne, Ohio. Spot welding of panels inside the tank for strength and to plug the rust holes. The tunnel is removed to get inside. The last step before reinstalling the tunnel is to weld the knee pad brackets in place. When the tunnel is TIG welded in place, the inside is sealed with fuel resistant epoxy.  

R68 crankcase repair

By Richard Sheckler –  Wayne, Ohio. Crank case repair. I was for the most part unemployed for about two years in the mid-1990’s. I had an ‘under the table’ job working on motorcycles for a friend and fellow collector. One time after some persuasive negotiating, I received payment in trade. That was a partial basket case 1953 BMW R68. The bike had matching serial numbers, to whom, if you are a collector, is regarded as significant. Karl B. a long time M/C race enthusiast and rider acquired the R68 from a family near White lake, Michigan. The bike had been
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R24 crankcase repair

By Richard Sheckler –  Wayne, Ohio. An R24 brought back. Scroll down for Richard’s story.         I met Garfield Smith (Petrolia, Ontario) more than twenty years ago. He mentioned that he had an R24 BMW which was made during his birth year 1949. This was also an important year for BMW, because they were in serious financial straights after WWII with the shackles of the Allied Military Command mandate not to manufacture motorcycles that could be used for making war. In 1949, the restrictions were lifted partially, allowing German firms to build motorcycles up to but not
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R69S crankcase repair

By Richard Sheckler –  Wayne, Ohio. An example of how a broken crankcase is repaired. It’s specialist’s work, nevertheless it shows that parts that are seemingly beyond repair can have a 2nd live. Broken connecting rod shoved through the crankcase between the two cam followers on the left side. Welding by  Mark Laree, Toledo The final touches with a needle scaler, steel shot and glass beads

Workshop manual R51/3 – R67/2

Click here to view and download PDF file:

Wiring diagram R50 – R69S 6V

Wiring diagram BMW R50 – R69S – 6V  (1955 – 1959) BL = Blau = Blue BR = Braun = Brown GE = Gelb = Yellow GN = Grün = Green GR =Grau = Grey RT = Rot = Red SW = Schwarz = Black VI = Violet WS = Weiss = White        

Wiring diagram R26

Wiring diagram BMW R26 (1955 – 1959)    

Wiring diagram R27

Wiring diagram BMW R27 (1960 – 1967)      

Wiring diagram R51/3 – R68

Wiring diagram BMW R51/3 – R68 (1953 – 1955) with brake light          

Road test R27

Road test of a BMW R27 – May 1964

Special Tools for Motorcycles

BMW catalogue “Special Tools for Motorcycles”         More to follow  

Wheel offset

Wheel offset for R51/2 – R68, R50 – R69S models (from “1000 Tricks für Schnelle BMW’s”)                

Motorcycle models

Overview of  BMW motorcycle models produced from 1948 to 1969 (specials not included) Click for larger image: Models & Production Numbers  

Valves types and related components

Overview of the different valve types and related components, used in the BMW 1 and 2-cylinder motorcycles 1948 – 1969

Fuel cocks

Overview of fuel cock types for 1 and 2-cylinders

ISO Metric screw thread

Overview of ISO metric screw threads M3 – M30. Commonly used screw threads on 1948 – 1969 BMW models are M6x1 coarse, M8x1.25 coarse and M8x1.0 fine.   The length of bolts and screws is measured like this:                


Overview of carburetor nr’s and settings  

Reading spark plug faces (Bosch)

A visual inspection of the spark plugs can serve as a good indicator of the condition and tuning of the engine. This Bosch sheet may help to identify the possible cause in case of trouble. (click to enlarge)

Spark plug tech tips (Bosch)

Guidelines for correct installation of (Bosch) spark plugs  

Overhaul of a 2-cylinder crankshaft

The photos are a compilation of the work done on different crankshafts: R67/2, R60/2 and R69S.                                                                    

R26, R50, R60, R69 – valve guides

No. 12/59 (166) November 19th, 1959

R26 – gasket on rear wheel drive

No. 2/56 (94) May 11th, 1956

R50S, R69S – hydraulic steering damper

No. 1/61 (179) July 27th, 1961

R25/3, R26, R27 Drive shafts

No. 1/62 (183) February 1st, 1962

R27 Spitting carburetor

No. 3/62 (191) July 26th, 1962