Predator 212 with gx390 carb jetting

Hey folks I’ve been away from Karting for several years and decided to get back in it. Our local track offers a gas pro class (stock appearing).

I have put together a 212 with cam, oversized valves, ported head, arc rod, arc flywheel with 32 degrees advanced timing, big pipe and gx390 carb.

having issues figuring out the low and main jet sizes on this carb. currently it has a 40 low side and 46 main. I’m thinking this way to big.

wont idle and falls on its face when given more than 1/4 throttle.
recommended jet sizes Or suggestions?

thanks in advance
 
Don,t know jet size,i run them out of the box.Sometimes they feel like the main jet is small.I change the low jet to stock from another carb and no more problem.That means the jet was stopped up on low side.I run the 390 on 3 different motors.
 
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