Jetting Question???

[joesal99]

I just installed a dynojet jet kit on my '03 400ex and it seems to be running way to lean and killing itself. It backfires quite a bit and seems to flood itself when it warms up. it has the dynojet needle groove 3, main jet adapter, and 146 main. I have a K&N filter and FMF PC4 slip-on. the fuel mix screw is at 3.5 out as the instructions say, but I tried it from 1 turn to 3.5 out. any ideas of how to get my bike running smooth with the dynojet kit I have on? I really don't wanna have to open that dang carb up again. btw this is my first quad, just lookin for some good info!

Sal

[Pappy]

maybe im wrong, but i thought the dyno jets were a bit larger (reference wise) then stock jets? if so, that 146 main maybe lean and you should bump to a 152 or 155.

also, are you running an airbox lid?

[joesal99]

Yeah I have the airbox lid on since I ride muddy and/or dusty trails almost exclusively. I'll try those other mains out though.

Sal

[cals400ex]

yeah, you could try the mainjet one size larger than the 146. also, is it backfiring and popping just when you let off the gas??

[joesal99]

well pappy and cals400 I ended up letting it sit for 2 weeks, no time, and fired her back up with a new tank of gas and it ran like a dream. just adjusted the fuel mix screw and idle. thanks for your help

Sal

[hondarider2006]

Originally posted by joesal99
well pappy and cals400 I ended up letting it sit for 2 weeks, no time, and fired her back up with a new tank of gas and it ran like a dream. just adjusted the fuel mix screw and idle. thanks for your help

Sal


Do a plug test....I did what the instructions said to do with that jet kit....Installed a 146...blah blah blah, and did a plug test, it was white as snow. Ended up with the 155mj. Just a thought;)

[jt911]

A sure way to tell when the jetting is correct is to install an air/fuel ratio meter.