another jetting problem HELP!!

I recentally put a pipe on my yz400f and i put a 45 pilot jet in like it said but the bike still backfires in the low rpm range and also when I rev the bike up. if there is somehting i can do to make this stop let me know. thanks

Did you use a new crush washer in the exhaust? It sounds like a leak at the exhaust where it meets the head. Have you adjusted your fuel screw out?

Hey no I didn't put a new crush washer in. can I buy one at a dealer? and also by accident i turend the fuel screw but i put it back at what I was told was factory 1& 3/8 turns out. if thes wrong let me know. the bike is also running rich. if you can help me that would be great.. thanks matt

allow me...ride below 1/2 throttle, but at a constant down a road somewhere. if it's smooth and not jerky your pilot is long as there are no other problems. do the same above 1/2...and check main. I put on my Jardine system, had the same problem as you and ended up at 48 PJ and 172/175 main. now, all is well.

vet28 :thumbsup:

Yes the crush washers are available at the dealer. Always tinker with the fuel screw regardless of the "stock" setting. That is merely a baseline. Where is it running rich? and why do you think it is rich? Smell? Performance? Plug? Exhaust?

When i ride below half throttle the bike is jerkey and not smooth..what should I do in this case. and i also know its running rich because of the color of the plug. i have the sock pilot in the bike still. the reason i think its running rich off the bottom is because when i rev the bike it will blow flames out the exhaust. if you know what to do to fix this let me know



It is blowing flames on the stand with no load right? I would say drop the needle 1 notch or leave the needle alone and go down 1 main size. This is only if it does the flaming while riding. If it is just on the stand forget it.

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