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Rejetting with new exhaust.

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Hello Everyone,

just found this forum and i hope you guys can help answer a few questions for me if you don't mind.

Just got a new xr400 and the previous owner had put a white brothers r4 exhuast on it and i don't think they modified anything else. my question is whether or not i need to make any other adjustments to the engine to accomidate the new pipe, re changing/adjusting the jets. any advice would be graciuously appreciated before it's too late!

Thanks

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First how do you feel it is running?

Have you taken the carb apart to see what jets and needle you have in there?

Does it pop on deceleration?

Experimentation will usually end with good results and teachings if you are patient.

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HEY FASTEST,

THANKS FOR THE REPLY. THE BIKE RUNS GREAT AND I'VE HAD NO PROBLEMS AT ALL. I DID FINALLY GET THE PLUG OUT AND THE TOP WAS A TAN COLOR WITH A BIT OF CARBON BUILDUP ON THE THREAD. PROBABLY ONLY 30 HOURS ON THE BIKE SO FAR. IT WILL POP ON OCCASION BUT VERY RARELY. I ALSO FORGOT TO MENTION THAT I PUT A K&N FILTER IN AS WELL. THANKS FOR YOUR FEEDBACK.

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I would say stick with your settings now if you like the performance. Regarding the popping on deceleration, this indicates a lean pilot circuit. Turn your fuel screw out to lessen or eliminate it. In truth you dont want to totally eliminate the popping because it will slow throttle response. A little popping occasionally is fine. Tan porcelain is what you want. Sounds like you got it, but I cant figure out why if your original settings were good unless of course the temoeratures change. I have to rejet between winter and summer and I always adjust the fuel screw every ride. :cry:

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