XR650L Smoking and Stumbling Off Idle

I just picked up a 2004 XR650L and have been running through the usual mods. I just got everything back together, but now it seems like it might be running a bit rich. It has a pretty pronounced stumble or stutter right off idle, and smokes a bit (blue smoke). I was hoping somebody had a similar setup and had some ideas. I'm running pretty close to sea level. Here is my setup so far:

White Brother E-series exhaust w/ 12 disks

Smog kit and snorkel both gone

Uni air filter

Slide drilled

Dynojet jet kit - 165 main jet, stock pilot jet, needle set at 3rd groove, fuel mixture screw out 2 turns

Any help would be appreciated.

Thanks

blue smoke? Black or gray would be rich fuel. Blue would be more of worn rings. Put a new plug in and check the color of the old one.

It just occurred to me that the smoking was oil and grease burning off the newly installed exhaust. I had to lube the hell out of it to get it on. In any event, I still need a solution to the off idle stumble. Thanks for the reply though.

Try turning the mixture screw in or out to simulate a richer or leaner conditon. I had a pretty bad stumble on my '93 650L, it turned out to actually be the main jet. I had a 165 in and it was too big. When I installed the 160 main, the stumble went away. I am running a Supertrapp racing series with 16 discs (loud), twin air foam filter, uncorked, de-smogged, Dave's mods, 160/60 jetting and stock engine. My bike runs perfectly and my elevation is around 500-1000ft.

Try turning the mixture screw in or out to simulate a richer or leaner conditon. I had a pretty bad stumble on my '93 650L, it turned out to actually be the main jet. I had a 165 in and it was too big. When I installed the 160 main, the stumble went away. I am running a Supertrapp racing series with 16 discs (loud), twin air foam filter, uncorked, de-smogged, Dave's mods, 160/60 jetting and stock engine. My bike runs perfectly and my elevation is around 500-1000ft.

165 DJ main jet is like 160 stock Keihin jet. I think your problem is in the stock pilot and air screw, you should be 55 pilot. Lean pilot will cause stumble off idle. I have that same exhaust and i think if you change that pilot and go 2 1/4 to 2 1/2 on the air screw like it says on daves mods you will notice a better response.

Check all that has been posted already. How many miles? You may have bad oil control rings. Or if it smokes only on startup, valve guide seals leaking.

When I first put my Djet kit in my old CV carb, I first tried the 165. It did something similar to what you stated. I had to go with the 160. Ran great after that. Although I am at 4300 ft.

165 DJ main jet is like 160 stock Keihin jet. I think your problem is in the stock pilot and air screw, you should be 55 pilot. Lean pilot will cause stumble off idle. I have that same exhaust and i think if you change that pilot and go 2 1/4 to 2 1/2 on the air screw like it says on daves mods you will notice a better response.

Yup I agree. This be the problem with yer poor throttle response, the pilot needs to be changed and etc as above. :applause:

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