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post #1 of 6 (permalink) Old 05-01-2007, 04:19 PM Thread Starter
 
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Weird Idle

So once the bike warms up and it's idling I've noticed that it jumps up to about 1600 to 1800 rpms for a short moment and then goes back down. Then it repeats it. I can give it a little gas while it's doing it and it'll go back down to 1100-1200. Anyone have any idea what might be causing this? It's not the routing of the throttle cables or the choke cable, I already checked those. I think it might be something in the carbs, but not quite sure yet.
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post #2 of 6 (permalink) Old 05-01-2007, 04:37 PM
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Originally Posted by asaracho View Post
So once the bike warms up and it's idling I've noticed that it jumps up to about 1600 to 1800 rpms for a short moment and then goes back down. Then it repeats it. I can give it a little gas while it's doing it and it'll go back down to 1100-1200. Anyone have any idea what might be causing this? It's not the routing of the throttle cables or the choke cable, I already checked those. I think it might be something in the carbs, but not quite sure yet.
When your carbs are out of sync you can get a fluctuating idle like that. Have you sync'd 'em yet? If not, I can search for some posts here about how to make a manometer for pennies (well, okay, a couple of dollars) and then how to actually sync your carbs. Not a difficult job at all; it just sounds daunting. And the results are immediate!

C
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post #3 of 6 (permalink) Old 05-01-2007, 04:49 PM
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you mentioned "when the bike warms up". do you have your choke engaged at that point, or is it past the choke need?
asking since mine will climb to about 2K rpm and drop back down to 1.5k once i reduce the choke step by step.

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post #4 of 6 (permalink) Old 05-01-2007, 04:58 PM Thread Starter
 
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Choke is definitely off. I only use it minimally when warming up the bike. The sync suggestion is a good one, i'm going to go pick up my vaccum gauge and check it out. I'll let you guys know the result.
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post #5 of 6 (permalink) Old 05-01-2007, 11:23 PM
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Rising idle can also be a vacuum leak. The lean (more air) condition will raise the idle some and be inconsistant. Just another thing to check, pinholes in vacuum lines, leaking or cracked manifolds (rubber carb mounts where carb joins the intake).

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post #6 of 6 (permalink) Old 05-02-2007, 03:08 PM Thread Starter
 
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Thanks for the suggestions, I've figured it out I believe. I changed the exhaust gaskets and while I was working on that I also made sure the vacuum lines were sealed/plugged right. I went for a ride and when I got back the idle was now at 1800 and not fluctuating any more. Turned the idle down to 1100 and there is where it stayed. Went out and rode some more and it's still working well.

Old exhaust gaskets were very thin and old, I replaced those with the screaming eagle kit I bought from the Harley shop down the street for 7 bucks.
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