1980 SR250 idle speed changes randomly

[asfi99]

I think I have an alternator issue with my 1980 Yamaha SR250, battery runs out of juice and this might or might not be related to the following (I am using an 8 cell Anti Gravity battery)

Bike starts and runs great but after running for a few miles when I come to a stop and bike is in neutral and idling then motorcycle idle speed goes up tremendously and it starts reving very high, if I play with the choke it seems to get normal for a few minutes and then it starts revving really high again.

Anyone has any clue or seen this issue before ? Just to be clear when bike starts it idle's normally and only after driving it around for a while the ide speed picks up.

 

[Sonreir]

Not likely to be an electrical issue. I would guess carbs. Possible air leak?

 

[Sonreir]

Moving to 1-800 section

 

[mArK47]

I've got the same issue, except it normally takes more than a few miles to start doing that. I deal with it by flicking the kill switch on and then back off just before it dies, and sometimes I can get it to settle into a lower idle again. Adjusting the throttle stop to a lower idele works better, but then it dies at idle next time I start it from cold.


I'd assumed I had a blocked pilot jet and was idling on the main jet, but cleaning the carb didn't change anything. Maybe I should spray some butane around the carb and intake when it's idling and see if it races to check for leaks?