Inliners International Forums General Discussion Engines 250 idle question

Here is my opinion on this problem. the vacuum advance on my engine connects to a port that is not full vacuum. it could be that you are hooking your vacumm link to full vacumm and that is why its advancing so far.

In my setup the port that the vacuum advance connects to on the carb leads to a very small hole inside the carburetor throat. when the butterfly valve is shut at idle this vacumm port is not exposed to manifold vacuum, then as you open the throttle slightly the butterfly valve gradually exposes the distributor connection to the manifold vaccum and starts to gradually pull on the advance mechanism.
There sholud be no advance during idle and only advance when you open the throttle. Usually that vacumm hose connector is just above the level of the throttle butterfly. if you are using any other vacum source , that is most likely your problem.