Fresh top AND bottom on 1986 LT250R. Boyesen Reeds, DG pipe, stock silencer. 260 main jet. Fresh plug, Uni pod filter.

Started it for the first time tonight.

Idles a bit high (even with idle screw all the way out) and choke makes little difference. Checked throttle cable, plenty of slack.

Within a few minutes the RPM's spike without throttle input.

I'm thinking vacuum leak somewhere?

Where do I start?

Help!

OldBikeDoc

 

my kehin carb i have to screw it in for idle to lower. but if you take catrb cleaner and spray it around intake boot it should stall it out when ya find the leak. if nothing happens pull your flywheel case cover off and spray around it it should stall it or bog it if seal behind it is leaking. good luck

 

Yes,pull the fly wheel off and check the seal.I just had the same problem.My seal had blown out,but was still in good shape,so i cleaned it up and pressed it back in.