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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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.

Leaking carburetor screw caps

When the screw caps on the underside of the carburetor keep leaking (after having installed new gasket rings), then the probable cause is the condition of the seat of the carburetor gasket. If you look closely, you will probably notice that the surface is rough, damaged or scratched. The solution is NOT to further tighten the screw cap: the gasket ring is not flexible enough to fill these small damages. The seats of the gasket rings can be machined, but if the damages are not too deep they can be removed by sanding the seat with a very fine grit
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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  

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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R27 Throttle assembly switches

3 types of throttle assembly/switch combinations were used on the R27 models 1. From nr. 372001 Turn signal switch with PN61318048152 and switch mount with PN32722072175                 2. From nr. 379795 Turn signal switch with PN61318048182 and switch mount with PN32722072180                           3. From nr. 385265 Turn signal switch with PN61318048183 (horn contact) and switch mount with PN32722072181 (sloping)                                

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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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

Foot brake lever pin repair

By Richard Sheckler, Wayne, Ohio  https://www.facebook.com/profile.php?id=100001965546450 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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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 or purchased here: Download Purchase