Cannot find right idle jet  By  glavey (Read 1,215 times)

Oh man, if only I had the money and didn't have A.D.D..


Well, I went out and cleaned the carb as best I could, put it back on and went for a spin to get the engine up to operating temp. Came back and tried, in vain, to tune the carb with these instructions. The adjustment screw was at 3 1/2 turns out when I started, now it is at 3 turns out.

I went back out for another ride to test what alleyoop said. At 15 mph, with the engine nearly cutting out, I was just barely giving it gas so I could only turn the throttle back to idle. The engine just slowed down and continued to almost cut out.

At 25, right at the point where the engine is on the line between struggling and running well, when I cut back on the throttle, it slightly speeds up then goes back to struggling.

At 35, with the engine running well, when I cut back on the throttle, the engine just slows down how, I think, it should. Although, to be fair, I really don't know what is normal for these engines; I had a factory 63cc before I put on the BBK and that was too lean all around so I don't know exactly to look/listen/feel for in a correctly tuned engine.

I also have another couple of symptoms to add; 1. when attempting to tune the carb, no matter how many turns out the adj. screw was, a quick blip of the throttle always resulted in a vraVROOOM instead the usual VROOOM.

And 2. No matter how many turns out the adj. screw is if I give the engine a quick and SMALL throttle blip, say 25% or less, the engine revs up with a vraVROOoM and then dies. If I give it a quick and LARGE blip, more than 33% or more, the engine revs up with a vraVROOOM and then settles back down to idle.

I'm willing to give tuning another shot, but I don't want to back the adj. screw all the way out. What is a good stopping point for turning out the screw?