14mm carb or 12mm?
Restrictor removed from intake or a good 14mm intake not 12mm?
Squish/compression set for head?
Head temp below 400 degrees F @ WOT?
Timing before jetting.
Ya first you have to time it correctly (17 thousand point gap, 16-17 degrees/mm on flywheel before top center
Not only will it keep you from blowing your kit.
It will help with jetting .
Case matched helps with jetting.
Compression affects jetting and tempature also ( 125-170 psi is good)
A head temp gauge not only keeps you from blowing your kit
It is a good tuning aid. With one you will prolly go over 400 degrees and
Blow your kit up
A metal mesh filter is a must
Tuned clutch and up gearing is a must with a kit too.
Keeping a stock bushed crank with stock low gearing will
Melt the bushing and boom.
A rebuild with a aftermarket needle bearing crank really is what is needed.
Search wiki all these things are there.
If you just slap a kit on your going to fail.
My 70 cc setups after doing all these things (not missing one of them) jetted
64-68 jet for a 12 mm bing/intake
70-74 jet for a 14 mm bing/intake
78-82 jet for a 15 mm bing/ intake
Do not run bike without taking care of these things (edited)