Hey, i have a modified brs42mm carb( stock carb) drilled slide, no airbox, no vacume tube...Now that its warm out at low idle i slowly get on the throttle and she seems to hit a flat spot then kickback/ backfire through the carb i can see the intake tube bounce when it does this....as soon as i give it a tiny bit more throttle she gets passed that point and just screems and runs nice and crisp.... I have everything changed in the carb except the pilot jet...im pretty set on the pilot jet being to small and its lean on the bottom thats why i have the flat spot which goes away at higher rpms where the main takes over....is this my problem?

 

What mods do you have?

 

1- Check rpm per Step 8 of Stock Carb Mods - Summary. Also verify float level is correct.
2- Turn pilot screw out from seat 6 turns - If problem goes away - Get larger pilot jet(47.5 or 50) and turn out 3 turns
3- If running with air-lid off and DJ needle - Run in the 3rd notch from top.

OMR

 

rpm is fine, pilot screw was out 6 turns, changing needle settings seems to have 0 effect [img]i/expressions/face-icon-small-shocked.gif[/img]. Carb did look like it had gunk inside it...thanks to the k and n filter oil....i prob should take it off and clean maybe theres a plugged jet or something somewhere. It ran fine when it was -10 or so but now thats its like +10 outside it does this...ill also do a low rpm run then shut off and check plugs to see the colors.