FMF Q troubles

Hi guys, newbie here, to both jetting & forums. I'v got an 03 wr 450 recently rejetted to 160 main, 48 pilot, 70 starter. Grey wire cut, throttle stop shortened, snorkle removed, needle clip stock position, stock pipe baffle out. After all these changes bike ran better than ever. Yesterday installed FMF Q and the problems started, hard to start, back firing with flames out the pipe and surging at steady throttle position. I'm in Dallas area elevation around 700 feet. Can anyone send me in the right direction or should I go back to stock pipe. thanks

Sounds far too lean to me. Are you still running the stock needle? Try running a larger main jet, probably a 170 and fixing the needle. Also, dont forget to adjust your fuel screw.

My settings are as follows-2500 to 4000 feet alt.

172 main

48 pilot

JD blue 4th clip from top

fuel screw about 1.5 turns out

The remaining jets are stock.

Just hauls with this setup.

Good luck and be patient when jetting. It ca be a real pain if you let it get to you.


you might want to check the pilot jet for clogging,if you have the correct short screwdriver bit you can remove it by just removing the float bowl drain cap 17mm wrench,i've had to do mine a couple of times,baja gas is not filtered and the fine stuff takes it's toll,:)

btw,the fmf pipe should't make that big of difference,i have one on my 04 wr

I put a Q on my 04 when I had it and it did the same thing. Start by opening up the fuel screw. If that doesnt help, put a fatter pilot jet and it will cure your problems.

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