idle speed issues

[russell205]

just got this old bike running its a

1980 xs650 with the b34 carbs when i start it it revs up to 4000 and stays there i already checked the trottal and floats alls good there just woundering if anyone has a good idea as to what to try

 

[5twins]

I don't even think these bikes will run as low as 400, do you mean 4000? Is this with the choke on because they will rev higher if it is. Other than that, I would check the sync. The right carb may be turned up way too high. Try backing out the sync screw on the linkage between the 2 carbs. That will slow the right one down.

 

[chopitdropit]

Just had same problem when I got mine running. Sprayed choke cleaner around intakes and it idled down...problem... air leakage. Haven't pulled it down yet, but seems to be an intake gasket sealing problem.

 

[xjwmx]

If you don't see an obvious air leak, check your valve clearances. I had an sr250 with that identical problem. The exhaust valve was so tight it was an air leak on the intake stroke.