Jetting Question

[npieces]

I'm running a 86 R, mild port job on stock jug, sparks TT pipe, keihin 38 mm pj /W/ 168 main jet and a new top end. My question/ problem is the bike runs great 1st- 3rd gear, at 1/2 throttle plus in 4th-6th the bike doesn't rev up great. It kinda sputters a bit. Now to the question, I had a 172 main in it to begin with and the sputtering was starting in 3rd gear, so it cleaned up a bit when I dropped to the 168. I was going to go to the 165 jet but was wondering if that might be to lean? Don't want to burn r up. Any input?

[superevil]

As long as your plug isnt showing lean already i would try it. I would also make sure its your jetting to. I had a bad jetting quest not to long ago that ended up being the plug cap

[npieces]

Good call! I'll check it out. Thanks!