Idle fluctuating up and down

J

Jsbowling42

New Member
Hello, I recently noticed that my idle is going high(slightly) and then lower, what I would call a hunting idle. I have a NT China carb and the 66cc engine is stock. My first thought was an air leak but then thought that an air leak would cause only high idle is this true? I took off the air filter to look at the slide as this was happening to see if there was any movement but there wasn’t so I could rule out the throttle cable I think. I was able to stall the motor with carb spray around the exhaust side of the base cylinder gasket but it’s so close to the case gasket I don’t know which it could be. Any ideas on where to go from here would be great thanks.
 
Try soap spray in the same area. It won't hurt the engine, and should show you a little more as to where the leak is.
 
It would be easy to GENTLY tighten the head/jug bolts, and/or replace the base gasket. The case gasket isn't that hard, just more of a disassembly/reassembly hassle.
 
Thanks I’ll try that in a bit and report back. Have you ever see an idle fluctuate up and down from an air leak? I would think it would just stay high.
 
Hmm.. well I’ll try the soapy water and fix the leak and go from there. One step at a time. Ha I’ll let you know how it goes.
 
Ohhhh been awhile. I believe you set the float to be even with the carb body when it just touches the valve. I meant to check for debris in the seat or other reason it would intermittently interrupt fuel flow.
 
So if your interested. I found the air leak, it was the seal behind the magneto. I guess it had vibrated it out. Carburetor cleaner made the engine die because it ran down into the magneto housing ha. I guess the soapy mixture Didn’t make it past the magneto housing gasket not really sure. But when I took the magneto housing cover off I felt the puff puff Like it was the end of an exhaust pipe lol
 
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