Author Topic: Sporratic High Idle  (Read 1667 times)

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Offline butch6924

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Sporratic High Idle
« on: April 10, 2013, 07:06:53 PM »
I'm working with a '74 TX500 with stock carbs rejetted for the exhaust and pods that have been installed.

After the bike warms up and I take it out a bit, at times, the idle will sort of hang. If I put the bike in gear, and slowly let out the clutch, and then grab the clutch again, the bike will often times come back to a smooth idle. Sometimes it takes more than one try. It doesn't seem as though the throttle is sticking. I don't think there's an air leak because it comes and goes.

So far, I have adjusted the idle thumb screw up and down and found a good idle point. I have checked the throttle cables to ensure they're giving the full range of motion.

Can you guys give me any ideas on how to trouble shoot the issue?

Offline guylr

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Re: Sporratic High Idle
« Reply #1 on: April 10, 2013, 07:07:16 PM »
In order I'd suspect:
1.Too tight valve clearances
2. Ignition timing advanced too far
3. Carbs slightly out of sync
4. Governor weights sticking
5. Carb throttle plates not centered in their bores


Now Retired Yamaha guy. Cut me and I bleed "Cinquasia Red"

Offline ellingvag

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Re: Sporratic High Idle
« Reply #2 on: June 27, 2013, 02:33:07 AM »
check for air leaks. A tiny air leak in the inlet will manifest differently depending on temperature, and could cause your climbing idle. you probably already know, but spraying some contact cleaner or similar on the inlet when idling will let you know if you have a leak - easy and cheap.

Offline dean

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Re: Sporratic High Idle
« Reply #3 on: June 27, 2013, 12:27:41 PM »
I had a creeping idle last week, and it was a vacuum leak: