Okay I got my trail ported cylnder on and it runs great, but i have a few ?'s for the experts. Okay Rick told me to run a 300 main jet, that was way to big (stock carb) so i put in a 280 and it seems to be better, what do you guys run? Also when you have your head cut how much do you norma'y get taken off? Also if anyone knows what is stock piston to head clearence?

 

come on people help

 

Yeah Rick told me to run a 300 and it was way fat. I ended up running a 270 I think. It kinda depends on what your elevation is. You can cut the head .020 and still be able to run premium pump gas. Not sure on the squish clearance. It will handle .020 no problem.

 

Step down one size at a time from the 300 main as needed . There really is no *magic jet size * , it requires careful tuning on an individual basis . That being said a piped , ported , 400 on the stock carb will GENERALLY run a 290 -300 main jet with the needle in the middle depending on if the airbox was freed up . Please do not rely on doing the plug chop thing . I see more poeple getting into trouble trying to read spark plugs , don't worry about plug color , feed the bike to much fuel and slowly lean it a step at a time til it cleans up .

Rick

 

Truth be told I could never make my trail mod work right with the stock carb. I think it was running out of fuel. After I went with the 39pwk all my problems went bye bye.

 

I switched from stock carb to the keihin 39pwk and mine seemed to run smoother. I dont have any porting done yet but the new carb seemed to make the throttle response better.

 

Yup! I will agree , the 39pwk does work better than the factory carburetor .