Pistons aren’t round

An article that explains why pistons aren’t round. Click on piston to open it:

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.

Installation instructions 12V dynamo system VAPE

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

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 3.00”    

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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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

Cylinder heads R50 – R69S: butterheads and LK heads

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

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    some of 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, as
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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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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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