Carberation

[Tone]

Hi all, Is there any way I can slightly weaken the mixture? I get a bit of popping on overrun and when I check the plugs after a good run they are a bit sooty, I did kill the engine as quickly as I could so it wasn't ticking over, any ideas? Cheers.

[A10Boy]

Hmmmnn, popping on over-run is usually caused by a weak mixture, yet you have sooty plugs.

I think the starting point is to check the ignition timing, then check the needle height. If the needle is too high it can go rich at 3/4 throttle and above, then lean on the over run as the "slow" jet is used, try adjusting the air screw half a turn at a time. as a rule it should be 1 1/2 turns out.

[MikeN]

Tone,popping on the over run ,I have found can be caused by pilot air screw not set quite right.Or air leak on mounting flange.
Mike

[Tone]

Thanks Andy and Mike, I have just checked and I had the air screw out just over two turns, changed it to 1 1/2 to give a go, cheers. Tone.

[trevinoz]

I used to get popping on over run with worn slide / body. A resleeve fixed this.
Trev.