Forum bmwbike.com

Hello!

I have a BMW R75 in May 1972. it has only 10,000 mil. but I have a problem rpm. when it is hot the rpm goes up for no apparent reason at 1600 rpm or 1900, my carbs are in excellent condition. I heard that it is possible to install a spring on the valve slid. sis who can say this will solve the problem ...thank you

Daniel

This sort of thing can happen if the carbs are adjusted/synched when the engine is cold. The bike must be run for 15-20 miles prior to performing adjustments.

Another thing it could be is a hanging advance unit. When the RPM rises and you're at a stop, try holding front brake and slowly letting out the clutch so that it drags the engine speed down to more normal, say 1000-1100 RPM. Will it stay there then? If so, then the problem is the advance unit. If it rises again, I'd look at the carbs.

Also, consider that you might have a vacuum leak. Spray some brake fluid, etc., around all the carb connections, especially between the carb and the head. If the RPM changes when you spray certain areas, that means the intake has a leak.

Kurt in S.A.