so i've read a bunch of the threads on the mysterious high idling.  most people point to being lean or valve clearance.  can someone explain the theory on why these things would cause the idle to hang like that?  it seems to me you'd have to be awfully lean to have the rpms hang like that at closed throttle, and i don't understand the connection between the valve clearance and idle speed.

thanks,
dan

If the valve stays open some mix will get out... and make it lean. Eventually you might burn a valve... but initially it will go lean, then quit running preventing that from happening till you reset the valve right.
Cool.
Srinath.

It could also be the choke hanging up, I know if I have the choke on full on my bike it hangs at 3,000.  Just a thought.

Quote from: seshadri_srinathIf the valve stays open some mix will get out... and make it lean. Eventually you might burn a valve... but initially it will go lean, then quit running preventing that from happening till you reset the valve right.
Cool.
Srinath.

yeah, but at that point it's already through the carbs and mixed.  which means air AND fuel is escaping, so how does that make it lean?

Quote from: jiggersplat

Quote from: seshadri_srinathIf the valve stays open some mix will get out... and make it lean. Eventually you might burn a valve... but initially it will go lean, then quit running preventing that from happening till you reset the valve right.
Cool.
Srinath.

yeah, but at that point it's already through the carbs and mixed.  which means air AND fuel is escaping, so how does that make it lean?

OK I was sorta too terse in the description... OK Intake valve being too tight and staying open will make it pop in the carbs cos the spark will ignite the mix which will bleed through the open intake and light up the mix in the carb throat. Exhaust valve being too tight will actually let it suck air/exhaust fumes when its on the suction stroke and hence suck less fuel air mix in making it lean cos its got air comming in.
Cool.
Srinath.

Thanks for clearing that up Srinath.  I've asked for an explanation on that before with no good answer.  

Rob