FMF jetting

[TRX400EX02]

My new FMF Q2 slip on finally came in. I also bought the FMF Power-Up jet kit to help me out with the jetting. I installed the pipe and fired it up. It didn't sputter or cut out, but it did backfire quite abit. So I figured it was lean. I took out the mainjet and it was a 148. The directions say that I should put in a 146. Wont that just make it leaner?

[TRX400EX02]

If it matters, I have a K&N air filter installed too.

[vpofthedrc]

Take it for a run, and pull the plug. If its white it needs more fuel, if it looks wet or very dark, it needs less fuel.

[TRX400EX02]

How many turns out should the mixture be? The FMF directions say 3.5 but it seems that everywhere else I look it says 2.5?

[speedracer350X]

Dude, I have a PowerCore4 and a K@N w/ outerwears , no airbox lid, but an outerwear cover also. It really opened my 400 up. Not arm wrenching wise, but a lot more responsive on the throttle, and a more smooth transition when going through the gears. ANyways, I started out with a 160 main, and actually worked my way back down to a 152 main. Stock I think is 148. I also played with the air/fuel screw a little bit at a time, it doesn't take much adjusting to make a difference, just go in small increments, and record your work. Currently. I put the airbox cover back on, the trails are soaked, and I must've had an 1" off water in the airbox after last time riding. So I have to take it out and see if I'll have to do some more adjusting. Take your time, record your adjustments, check your plug, and listen/feel the motor. You'll get the hang of it.

[TRX400EX02]

Thanks for all the help.