I have tried 3 sets of carbs and several different people have tried to tune the 1971 R75/5 with little success.

I installed later model carbs last week which seem to help a little. The bike is rideable and seems to run ok at any speed above idle. However, when I try and balance at idle using the grounding method, the left side dies. If I rev any, the cylinder kicks in at any speed above idle. It is the left side only and right side idles well.

I cleaned and blew air through the carb, checked cables, choke off,diaphram appears OK,new plug, new boots from carb to cylinder, switched sides with coil/plug wires. Took cover off to look at points and it appears they are ok, but not sure how to tell if they are not (they are new). If the shaft is bent, how can you tell?

Also- just curious- the cover says "Hilderbrand" on the front and inside has a BMW logo, below which is a little "clock face" with 70 in it ad 11 to the rigt of that. It has a part # 1.255.0059 which does not match the parts list. Does anyone know anything about this cover?

Thanks for any ideas/info!