Rebuild BMW R75/5 Bing CV Carburetors



Bing constant velocity carburetors as used on BMW R75/5s and up are wonderful devices, generally trouble free and long wearing. Yet overhauls are still occasionally necessary, as we found with our subject 1973 BMW R75/5. Suffering from deteriorated jet and throttle shaft O-rings, the carbs were impossible to properly set and the only solution was a full overhaul.

For parts, we turned to the Bing Agency International. After describing our carburetors’ condition, Fay Laughridge suggested their #6 32mm CV rebuild kit, which comes complete with every gasket and O-ring needed, new throttle slide diaphragms, new slide needles and jets, new floats, float pins and float needles, new float needle seats, and new throttle plate screws.

A comprehensive Bing rebuild isn’t cheap. Our kit with optional needle seats came in at $261, and while you can source some of the bits cheaper the ease factor of picking one part number and knowing you’re getting everything you’ll need is huge. Further, as near as we can find, the Bing Agency is the only source for replacement float needle seats. The Bing Agency offers troubleshooting help and can also supply Bing manuals. BikeMaster

The Bing Agency also offers a float and bowl kit with alcohol-proof floats. The stock floats aren’t alcohol proof, but they seem to hold up reasonably well over time. Whether you want the upgrade — we went stock — is a judgment call you’ll have to make.

While this is a somewhat fiddly rebuild, it’s certainly within reach of the average mechanic. The trick, as always, is to take your time. When something doesn’t want to move, find out why before you force it. The only special tool required might be a carb synchronizer for tuning, but a good ear can do well on a twin. That said, for this project it’s essential to have a good manual on hand to help with parts identification and location, and final tuning.

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