FCR carb jetting

[hondarider2006]

A friend oh mine got a complete trinity system and a FCR 39mm carb off of e-bay for his KFX 400, its jetted right now with a 158mj, and the top end is great but we are having some other problems. If you are just sitting on the quad revving it, like blipping the throttle, its misses a lot, and when coming out of a corner and hammering it, it sputters..misses....and than pickes up and goes. I was just wondering if I could get some info on jetting this carb, and what we should start doing to fix this problem. Any info would be great!!! Thanks -Nick-

[cals400ex]

there may always be slight hesitations out of this fcr carb. the accel pump shoots gas for a long time and it is too long for these bikes. i would take the top of the carb off and check what needle you have in there and what clip position it is on. i have an EMP needle (the one sparks and C&D says to run) that i have never once used. i am selling it if you want it. see what pilot jet is in there and where the fuel skrew is set at.

[hondarider2006]

Alright we will look at the Pilot and air screw. What is the difference between the two needles??

[cals400ex]

the stock needle in the fcr is an ocemr and this needle is an ocemp. this means the diameter of the ocemp needle is a tad richer. this difference should be most noticable around 1/8 throttle but anywhere from idle to 1/4 throttle could slightly be noticable. my buddy just put in an ocemn which is one size richer than the ocemp needle. it is a tad rich for his bike but he is leaving it in there. by the way, we run our needles on the 3rd clip position from the top.

see what clip position he is on too. also, make sure his clip is in good shape. these needles don't come with clips so you have to purchase these seperate. however, if your clip on the needle in there is in good shape with no bends, you can most definately use that one on another needle.