View Full Version : which jet combonitation.
400EXracer74
03-19-2005, 04:17 PM
currently i have a 170 main jet in my 400 ex and i think a 45 pilot jet. it runs good all the time but i dont know if thats just cuz it is running lean. ive heard lean runs fast and hard bust isnt good for the 4 wheeler engine. i dont know if this makes much sense but i also dont want to do anything bad to my engine. i have an FMF powercore 4 exhaust k and n filter and no air box lid.
cals400ex
03-19-2005, 11:29 PM
if your running keihin jets, i wouldn't run larger than a keihin 158-160 in cold weather and low elevation levels with your setup.
Screamin440
03-20-2005, 07:28 AM
Lean is mean but fat is happy. I prefer mine a little on the rich side to keep cylinder temps down and to prevent pinging.
400EXracer74
03-20-2005, 06:06 PM
i have a dyno jet 170 in and its warm. ya think thats ok?
TravEX
03-20-2005, 07:26 PM
http://www.cdracingonline.com/id57.htm
cals400ex
03-20-2005, 07:33 PM
i haven't tried dynojets out but from what i read a dynojet 155-160 should be plenty. your bike may seem to run fine now but it should run better by going a little smaller. good luck
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