The dynojet doesnt include a new pilot jet and I think thats what you need.

 

You might start by looking at the spark plug. It's a good indication of lean or rich.

 

With the opened up intake & exhaust you need to rejet. The fuel screw does not have the ability to fix all your problems.

 

Whiteman,
My bike was doing that in florida, I was running to rich. After I fixed that it would still backfire and pop occassionally. I then removed the smog controls and the bike quit poping and backfiring. The bike runs very good now and also seems to run cooler. Duane5157 also if you have a vacum leak it will cause a lean condition and backfire.

 

I will check the plug when I get home this weekend! To see if it is indeed running rich or lean! Thanks for the help so far guys, great forum! Glad to be a KLXer

 

You have to get the jetting figured out. Main, pilot, needle/clip and fuel screw. The spark plug is not a very accurate way of telling how your jetting is on these types of bikes. When I had my CVK I had a Four Stroke Works jet kit with various size mains and pilots. A good place to start would be 130 main, 40 pilot, NTC1 needle, needle clip 3rd from top and fuel screw 1.5 turns out.

 

Hey guys I'm a newbie to the forum. I installed a Two Brothers exhaust on my bike & was assured it would work with
stock jetting. I have done a few mods but no jetting. My bike will pop when I let off the gas when goingdown the road,
but only when I let of most of the way.I can hear the popping pretty good, but no flames. Is this normal? I hear
some dirt bikespopping. I will be checking the spark plug.

Tim

 

Tim1, welcome to the forum. Even with a slip on it would be wise to open the aixbox up some and then rejet. There are quite a few that are running the 2bros slipon they should be able to help in getting the jetting close the first time.

 

I have a 40 pilot, two turns out of the FS, N1TC2nd notch w/ collar,& KDX snorkel. With the first baffle drilled, it never backfired.Then I drilled all the way to the end(about 7 inches into the muffler) and now it has a very minor "pop pop pop" when I abruptly close the throttle.