Idles speed increases

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Idles speed increases

Ruffles
Hi everyone.  I'm completely new to motorcycles and I picked up a non running 1980 CB750F for my commute to work.  Initially, it would only fire on starter fluid so I pulled the carbs off and cleaned them.  I didn't adjust the pilot screw as I didn't have the flow tool to synchronize the carbs.  Anyhow, I got it back together and it's running except I'm having a problem with the idle speed.  With the bike stopped in neutral or with the clutch in, I can get it set to idle around 1000 rpm.  When I ride it, however, and pull in the clutch, the idle climbs to ~3000 rpm.  I'll bring it to a stop and try to adjust it (without burning my hand too badly) and it will eventually come down.  Then, when I ride again, its back up.

I've checked and there seems to be plenty of slack in the throttle / clutch cables so I don't think that's the issue.  One thing worth mentioning is it's got a pretty big hole in the right side muffler (I've got a new Mac Slipon on order).  Do you think that once your moving, the air going into or out of the hole could be messing things up?

Thanks for your help guys.  So far, I'm really learning a lot from working on this thing.  As stupid as it sounds, I was really proud of myself for getting it to start.  This is by far my most ambitious project and you get a real sense of satisfaction wrenching on something and then being able to ride it around.

Steve
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Re: Idles speed increases

dylansdad022102
hey there i had a similar problem and it turned out one of my float heights were not set right and would allow a little more fuel in the bowl then the others and would trickle up the idle jet. check you float heights.  i set mine and things are good. you can make your own carb sync tool with airline tubing for a fish tank and some atf fluid. look it up on the internet. and a hardware store should have the adapter you screw into your vacuum ports. or order from z1enterprizes.com the adapters are like 16 bucks for all 4
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Re: Idles speed increases

Ruffles
I think I got this sorted out.  I rebuilt my carbs again - this time paying special attention to the idle passages.  It appears that my floats aren't adjustable.  I put it all back together and while the idle was consistent it was high and I was out of adjustment on the carb idle screw.  After a lot of tinkering and burning my hands trying to adjust it, I found my choke wasn't opening completely.  After fixing that, It appears to be running and idling well.

Now, on to the charge problem...

Thanks!