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Main Area => General GS500 Discussion => Topic started by: jiggersplat on March 15, 2004, 05:19:03 PM

Title: valve clearance = high idle?
Post by: jiggersplat on March 15, 2004, 05:19:03 PM
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
Title: Valve open...
Post by: The Buddha on March 15, 2004, 05:28:48 PM
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.
Title: valve clearance = high idle?
Post by: sprint_9 on March 15, 2004, 09:34:31 PM
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.
Title: Re: Valve open...
Post by: jiggersplat on March 15, 2004, 09:46:27 PM
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?
Title: Re: Valve open...
Post by: The Buddha on March 16, 2004, 07:23:55 AM
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.
Title: valve clearance = high idle?
Post by: 500rider on March 16, 2004, 08:41:04 PM
Thanks for clearing that up Srinath.  I've asked for an explanation on that before with no good answer.   :thumb:

Rob
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