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NoOne65

Fast idle

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After sitting for the better part of a year my 99 Bird (I occasionally cranked it and let it run also fresh gas); the last time I started it it would idle fast about 2100 RPM. I took the tank off to look and cleaned the intake with some carb cleaner, checked for air leaks, lubed the cable and throttle bodies, I also let the idle adjustment all the way out. It ran fine for a little while...maybe an hour or so then back to high idle.

 

 

anyone have any suggestions?

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First, I'd let it warm up and set the idle then.  Let it cool then see what it does. 

 

I think I had an issue where I felt the idle was too low, so I bumped it up a tad once it warmed up.  I'd never adjust it cold because it should run faster when the engine needs warming.

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Most likely "element set , wax " Part 8 if you go to "Throttle bodies " for our bike . It basically bumps idle speed when coolant is cold . Once it is warm the small pushrod should retract . Most likely it needs some lubricant .

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2 hours ago, NoOne65 said:

It ran fine for a little while...maybe an hour or so then back to high idle.

So while running the idle went up, or after parking it and it cooling down it was high on the next start?

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If it's only getting stuck high after a cold start I'd say it's the wax unit or something else in the fast idle circuit getting stuck, otherwise probably not.

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Speaking of which.  Mine's too low and I thought about adjusting the pushrod on the wax unit, tho I haven't investigated it beyond looking it up in the manual.  The book warns not to mess with the adjustment.  Is there any issue with adjusting it?  I assume it's just an emissions reason that they say not to mess with it, but wondered if there's a real reason to not mess with it, like maybe something can be damaged by adjusting it.

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The shop manual calls for an idle speed range of 1,050-1,150RPM at normal operating temps. A cold idle speed will vary per circumstances, but an additional 200-800RPM is considered within the normal range. If you have an on-board voltmeter, you may notice the alternator isn't happy at lower idle speeds (charging rate at less than 12.8v) so some folks will adjust it to the upper acceptable range (1,150RPM @ normal op temp) to keep the charging system happy. That sort of adjustment seems to have no negative consequences. This can be helpful if you have additional current draw for any accessories.

BTW, I've never personally seen a cold-start wax unit fail, but I suppose it's remotely possible.

Edited by ironmike

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Bird loves revs. I set the idle on mine to 5500rpm to help launching. Hell, it spends most of it's time over 9k. I can't see wasting time with " the idle speed"....

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11 hours ago, Zero Knievel said:

First, I'd let it warm up and set the idle then.  Let it cool then see what it does. 

 

I think I had an issue where I felt the idle was too low, so I bumped it up a tad once it warmed up.  I'd never adjust it cold because it should run faster when the engine needs warming.

 Its not running low but running high...and high idle is at 2100 rpm roughly

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