AF adjustment on new carb makes no sense  By  Deleted (Read 648 times)

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Alleyoop

Probably way too rich. Taking the air filter off still leaned it out slightly, but not enough to notice since it was still way too rich.
You have installed, which is reasonable if you have a bbk. is way too big for a stock 50cc.
get main jets 75, 70, and 65.
Then start going down in main jet size. When it dies or has surging due to being too lean when you open the throttle you went to lean on the jet size, put the one you last had in it and do a plug chop to determine if you need to go up or down 2.5 in jet size.
when you're close, taking the air filter off will make a difference.
if way to rich, no noticeable difference.
If slightly rich, it'll run better at top end.
if slightlt lean it'll run much worse.