1978 ATC90 with Pro pipe, jet size. Runs decent but pops out the ehaust

[booblinker]

I have a 78 ATC90 with a 73 motor that has full aftermarket propipe exhaust. It pops, So I am thinking I need a larger main jet, maybe move the needle. Any suggestions?

[slashfan7964]

Try leaning it out a little bit first. A really rich running motor might seem to run fine but pop a lot, especially on deceleration.

[C.J]

Try leaning it out a little bit first. A really rich running motor might seem to run fine but pop a lot, especially on deceleration.

No. It'll be lean already if its got the stock jets in it,,, You can try raising the needle to see if that helps any. If it helps clear it up then you can either run it like that or get larger main for it

Where is it popping at though? On decel? As youre pulling through the rpm range? If it's idling and you nail the throttle does it die and fall on its face or what?