250sx jetting question

[Chris070780]

I have an 85 250sx with a uni filter and stock muffler with baffler/spark arrester removed. The other day I did the throttle chop test from full throttle. I took the plug out and I didn’t like how white it was on the electrode. Stock jet was a 130 and I placed a 132 in there. The color got a little darker on the plug with the 132 jet, but I think its still a little to lean. I would like to run with no air box lid. So what size jet should I go with? Would 138 be too much? As of right now I am experiencing no stumbling and the motor is running good, but feels a little down on power. I want to run an open lid on the air box safely to get a little more power, but I think the 132 is a bit to lean. Anybody have any info?

[Chris070780]

Blawww, after doing some reading it seems I am looking at the wrong part of the spark plug. I guess I need to be look at the base of the plug for the jetting and not the electrode. This sound right? I think I remember it being more black than anything, so I guess I may be rich.

[MTS]

hmmm i had always thought that white on a 4 stroke was good...like a car..but i guess i culd be wrong..lol...i have close to same thing you got its white on the plug but it stumbles a bit..but i figured that was my crap ass clutch.,.huh

[Chris070780]

hmmm i had always thought that white on a 4 stroke was good...like a car..but i guess i culd be wrong..lol...i have close to same thing you got its white on the plug but it stumbles a bit..but i figured that was my crap ass clutch.,.huh

Well now that I understand that the Base of the plug show jetting I am not worried about the electrode. The plug only had about 5 minuets of riding on it so I assume the electrode didn't have time to develop its full color, so the shininess of the new plug was still coming through. The color of the electrode will clue you in if you have the right heat range of plug.