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Persistent bog after airbox mod
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Posted by: dhph

I recently removed the snorkel and drilled a few holes in the airbox on my son's Kymco Mongoose 50 (2 stroke). At the same time I replaced the stock 80 main jet with a 100. The engine still bogged badly just past idle so I adjusted the air screw to the point where it is fully seated, which seems to be the best position.

With my son driving, the quad seems to run fine, but when I take it out for a test run and get on and off the throttle aggressively on some tight, bumpy trails I can still get it to bog intermittently. Does this sound like there is still some jetting work to be done (maybe a bigger pilot jet since the air screw is already maxed?) or is this just "normal" for a 180 pound guy pushing a 50cc motor that hard and not likely to happen with my 50lb son on it (he's not at the point yet where he can ride that aggressively through the trails to test it out)?

Posted by: ww228king

too mush air for that little carb.. only take the snorkle off and remove the rubber in the intake hole... turn the lid backwards to keep dirt out

Posted by: dhph

I put some rubber plugs in the holes I drilled, then removed the snorkel/rubber insert and turned the lid around. I also backed the air screw out a bit to idle peak. It seemed to run better this time. It still bogged out when really getting on it and slamming the throttle open and shut, but not as easily as before.

Probably related (although I'm not sure it squares with the too much air hypothesis) it fouled a plug, which I replaced before the above changes and testing.