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View Full Version : Jetting questions



chris93555
10-17-2010, 03:51 PM
I have a 2008 TRX400EX, with FMF Header/exhaust, K&N air filter and power lid. Everything runs good until near max speed, I'll be in 5th with the throttle fully opening and hitting speeds, i'm guessing around 50-60mph, and it starts to bog down and lose speed, I also notice there is fluid coming out of the exhaust. I'm running without any plastics if that helps at all (required to get to carb), current setting is 170 main, 42 pilot, needle at 4th groove, running at 2200 above sea level, and it's 82 degrees out, What should I do?


From what I have learn the last couple of days, pilot/mixture deals with idle and low throttle, needle deals with mid range and main jet deals with max range, so if I change the main jet 168 should this fix it? or should I go lower? I've been reading the FMF booklet that came with the jet kit and it seems like there setting are not working, this is what the booklet says to do, use stage 2 settings with after-market exhaust, air filter and remove air lid, for use under 3000 feet, use main jet 170, keep stock 38 pilot and needle on grove #3. none of this setting seem to work,is this normal?

honda400ex2003
10-17-2010, 05:31 PM
i would go to about a 165 and see how it does there with the needle 3rd clip. leave the 42 in go about 2.5 turns out on the f/a and you should be good to go imo. maybe a 162 but i would say that a 165 should be close. steve