42/160 idle is also way too lean. I'm betting that is what caused it.
If you are on a tuned cylinder, I am guessing you should be somewhere richer than a 38/120 at the leanest end.. and maybe a 52/140 at the richer end. Anywhere inbetween those two could be the correct one as well. You would have to test them and confirm.
If you are on a stock 150, or Stock 200 then you should be at stock idle jet.
Range of idle jets I would guess you should be in (from richest to leanest and showing the air fuel ratio in parentheses after each):
What you have in there now, 42/160 (3.809) is like 4 or 5 sizes leaner than the leanest I mentioned!
Just as an example.. a stock Stella 150 idle jet is 40/130 (3.25), and a stock P200 idle is 55/160 (2.909).
The air fuel ratio numbers smaller equals more rich. bigger equals more lean.. so regardless if your engine is a stock 150 or stock 200, you are still way leaner than you should be for either of those engines.
Last edited by swiss1939 on Thu, 12 May 2022 01:29:38 +0000; edited 4 times