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

A comprehensive list of special and generic tools

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.

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

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  

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.

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

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

Very informative video! https://fb.watch/gQycYmmz_h/    

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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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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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: https://bmwclassicmotorcycles.com/index.php/tools-products/bmw-r50-r69s-motorcycle-restoration-and-service-manual.html   BMW Factory manual – can be downloaded here: https://www.bmwclassicmotorcycles.com/parts/bmw-service-sheets/1760   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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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:                    

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

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

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

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.

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.

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

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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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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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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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            

Very informatieve article by Duane Ausherman on “butterheads” and LK heads: http://www.w6rec.com/duane/bmw/head/

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

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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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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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.  

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

Overview of carburetor nr’s and settings  

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