OK guys and gals, I have been a member here for a long time and you guys have to be the smartest ATV folks I have ever talked to. So even if you guys don't have any experience with the KFX 700, I need some help and or ideas on jetting this beast. Yes, I have a post over at Kawieriders also.

Here is the deal. I have added an HMF dual exhaust, Twin Air filter and opened up the stock snorkle along with adding a second one. This let the bike breathe a lot better. The stock jetting was 135 main in the front carb and a 140 main in the rear. I jumped them up to a 150/155 and turned the rear air screw out some.

Now the bike has ran great. But, the powder on the cylinder exhaust pipe burnt and HMF says that could be a lean condition or excess fuel from being to rich. My problem is the bike runs real good except for when it gets real, real hot in which it will not always idol and on a rare instince I get some poping when I let off the gas.

So, any of you with some ideas. Please bring any and all.

Thanks,
Jay
BS Racing

 

Check your plugs and see what color they are. Black/rich, white/lean. Just from doing this, you can learn a lot.

 

Everything is a solid tan color on the plugs except for the outer ring where the threads are. The rear cylinder may be a little lighter but it is very, very slight. I will have pics of them up on Kawieriders tonight I hope. I also get enough fuel coming out of the carb vent line hanging down the left side of the motor that it has turned blackish. Normal?

Jay
BS Racing

 

I would say both the popping in the exhuast and the hot pipe is due to lean. You might not be able to totally eliminate the exhaust popping, but try 1/4 turn more rich on the mixture screw.
If the drivibility is good, (easy to start, no bogging, no missing, no flat spots), and the plugs are tan, Id say its good, and the hot pipe may be due to thin wall pipe.