Over-rev at idle

Hi All

I’ve got a 210 with all the all the usual stuff on T5 4th, matched cases, 26mm carb, r/h jl pipe, and lightened flywheel. The scoot was running well up until a few days ago when it started to over-rev at idle. It would be fine the first time you start it but after about 5 miles starts to over-rev. I have done the easy stuff checked throttle cable. Cleaned, checked and refitted the carb with new gaskets and still have the same problem. The plug colour is fine so I don’t think it’s an air leak but have not ruled this out yet. What would cause this sort of problem? Is it possible that the clutch side seal or the flywheel side seal has gone and this is causing the scoot to overheat or is there something else that could be causing it.

Hope you can help

Hi All

Have checked the flywheel side seal and it’s clean and there seems to not be any leakage. Check the cylinder head and all was well there the plug colour is perfect. I have drained the engine oil, well what was left of it as there did not seem to be much in there and could not really tell if there was fuel in there but when I top the engine back up with oil and started the scooter up it started smoking really bad I can only assume that the clutch side seal has gone and this is causing the over rev at idle. If this seal is gone would this cause the problem I am having?

Thanks for all your help

Yeah if you’ve checked all that LI-ralph is right. Look for fuel seepage from the seal. If its bone dry look elswhere. Look at the cylinder head as well.

Sounds like an air leak, maybe from the magneto side oil seal. The idle rises with a warm motor if the mixture is to lean.