Carb. idle screw does not increase RPM.

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onanysunday

New Member
Apr 21, 2011
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St. Paul
Dellorto SHA 14.12

My bike would not run because of an intake manifold air leak. Teflon tape had been attaching it and it was loose even when the carb was clamped all the way tight. The outlet on the carb is 2mm bigger than the inlet on the engine. I fixed this problem and made a carburetor manifold sleeve out of a coiled strip of aluminum. The carb is now connected rock solid to the intake on the engine. However, the idle adjustment screw still has very little effect on engine idle at operating temperature. I turn the idle screw all the way in and it just barely raises the rpm when screwed all the way in and the engine dies. I've seen other threads relating to the issue and they all mention air leaks as the reason for this happening. I thought I had fixed that problem but it still won't idle. When I got the bike, I noticed one of the two screws that secures the carb top/lid is stripped and will not screw half of the carb top completely down. Does this pose an air leak problem? Or is this area of the carb. not have to be airtight? For instance, my throttle cable goes through the carb top and that connection is definitely not airtight, should it be? Or is the only airtight connection for a carb that really matters the one between engine and carburetor?

In the meantime, I've tightened my throttle cable as much as I can to compensate for the idle screw not working. Right now it just BARELY keeps idling due to low rpm. But is there any chance that I'd be able to ever get that idle screw working on the carburetor again?