Quick Help: Pilot air jet setting? WR400

I think my WR400 has a FCR 41 on it, anyways, I didn't realize the pilot air jet was adjustable and didn't count how many turns out it was, I just put it back together and forgot and left it turned all the way in. Now the bike won't idle without choke and wants to die in the low end, where should I start for tuning it, 1 1/2 turns out?

I assume that is what is causing it, nothing else was changed, everything was just cleaned and it wasn't too bad inside.


Here is the carb, not sure if its FCR 41 but it doesn't look like the stock one.


Pilot air jet on the left..


Typical stock setting is 7/8ths of a turn

Cool Thanks. I will set it to that and see how it feels.

Another thing, was taking the endcap off the FMF exhaust, every bolt popped like they normally do when they are stuck. Turns out every single one of them just snapped in the middle, half are stuck in the pipe and the other half in the endcaps. Excellent idea to use mild steel on mild steel with shitty hardware on exhaust FMF. Luckily its not too much louder.

Once you get the broken bolts, replace with stainless steel (high grade) and use anti-seize. All joints and bolts on the exhaust need anti-seize.

They arent coming out. they broke in half and there was a stud left sticking out of the muffler, i let them soak with pb blaster, then tried to get the studs out, and those snapped flush with the endcap piece. I will call FMF on monday, what a POS.

I tried ~ 7/8 on the pilot air screw, it wouldnt idle at all. Put it to about 1/2 turn and its ok. My accel pump diaphragm is pretty nasty, it probably isnt working right, so if you give it too much throttle it wants to bog.

I need to find out what model of carb it is, and then I wrote down all the jets and the needle/clip position, etc.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now