I think it's called a hunting idle?

Hey my VFR tach needle at idle tends to sway back and forth.

It's a relatively steady swaying of the tach needle an eighth of an inch or so. It stops pulsating anywhere above cracking the throttle.

What are the possible culprits?

Pc3 didn't change anything. Nor did new plugs. I'm assuming it's the idle valves out of synch. Bike has 30k on odo.

It's been doing it as long as I've owned it (1 year).


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Not sure if you meant the throttle body butterflies (sync) but that is what leapt to my mind.
John

 

I disconnected the PAIR system & my missing & idle fluctuations STOPPED COMPLETELY. Idles rock solid at 1200 now.

 

Could be valve clearances and then throttle sync, but I doubt it. Probably the PAIR system mentioned above

 

PAIR is blocked already. Still have the wires connected though for the solenoid. Flapper is still connected.

Valves?? Yikes!!


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Clean the throttle bodies including blowing out the starter valves with carb cleaner. I've got the same milage and cleaning TB's smoothed out my idle. If the starter valves have never been synced then that may need to done if the idle doesn't smooth out after cleaning.

 

Most motors fluctuate at idle... Unless this seems excessive? Sounds almost like a non-issue but maybe I'm not understanding completely?

 

I've seen video of VFRs idling without the degree of fluctuation mine has. (1/8-1/4" of swing at needle tip).

I previously tried seafoam in the gas and dribbling it into open throttle venturis so I'll have to go back and make sure I hit the smaller apertures on the starter valves.

I also sprayed throttle body cleaner but again I probably missed the small starter valves.


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