Help!! Is it time to rejet?

[jdim100]

I have an '06 brute 650i with the below mods:

K&N Air Filter
Dynatek CDI Box
HMF Utility Slip On

I have not rejetted the carbs yet, but I pulled the plugs and they still look good. My problem is up to about 1/2 throttle, the engine misses and backfires. Anything above that it runs great. Should I try to rejet the carbs or do you think it's another problem? If I should rejet, would a Dynojet kit be the way to go. They seem to come with really detailed instructions for the mechanically challenged person like myself. Thanks.

Justin

[NMKAWIERIDER]

Originally Posted by jdim100

I have an '06 brute 650i with the below mods:

K&N Air Filter
Dynatek CDI Box
HMF Utility Slip On

I have not rejetted the carbs yet, but I pulled the plugs and they still look good. My problem is up to about 1/2 throttle, the engine misses and backfires. Anything above that it runs great. Should I try to rejet the carbs or do you think it's another problem? If I should rejet, would a Dynojet kit be the way to go. They seem to come with really detailed instructions for the mechanically challenged person like myself. Thanks.

Justin

Interesting because most 650s have the #40 pilots already fixing the low or slow leaning problem that comes with the CDIs, and the slip-on is a maybe on jetting, but from like 1/4 throttle up. Hmmm...I might be tempted to see where the A/f screws are set. Should be about 2.5 turns out. Set then at 2.75 or 2 &3/4 turns and see if that makes a difference. If so, it should only to about 1/4 throttle where mains start flowing. There if it still has an issue, try shimming the CV needles up to 40 thousands. If that helps but doesn't get it all out, go up one size on the main jet and check to make sure you do have #40 pilots. If not, get them and reset your a/fs to 2.5 turns out.

[jdim100]

I appreciate the great reply. I'll give your suggestions a try and see how it goes. Thanks again.