quick jetting question

[b0rn c0nfused]

Just rebuilt my 400ex mods are 11:1 wiseco 87mm piston, stage 2 hotcam, white brothers e series shorty exhaust and no airbox lid. I have a 42 pilot and a 155 main did a plug chop and the plug is a light black color. How is it rich? Most people are running a 170 main. Should I adjust airflow screw or go to a 150 main? (Air flow is at stock settings)

[Pittsburgh400ex]

Maybe a dumb question but is it an old plug? I have 11:1 426 same cam no lid and k&n. I run 170 @ about 2000 feet. Its a little rich but i want it that way. 3-1/2 turns out on your air screw?

[b0rn c0nfused]

Nope brand new plug not sure what the elevation is.

[Pittsburgh400ex]

What brand jet? A 155 Mikuni is very close to a 170 dj. I think 166 exactly.

[b0rn c0nfused]

There keihin jets thats the weird part.

[JOHNDOE83]

If you didnt physically cut the plug open, you never saw main jet on your plug, hence the name "plug chop".

What you saw was your pilot and needle setting, which I guess from your description appear to be fine.

Main jet should IMO deffinetly be over 155, I would buy jets in incriments of 5 all the way up to 190, start at 180 and see if it can fully rev out.

If it stutters and wont fully rev out at WOT, back down incriments of 5 till it stops and fully revs out.

Without actually cutting the plug open, this is the only way to properly tune main jet.

[b0rn c0nfused]

i did actully CUT the plug. Would posting a picture of it help any?