Bike sputtering

Lately my bike is sputtering in the lower RPM's when I'm riding. If I twist the throttle the enging revs smooth and has good power.

I just did the BK Mod but that didn't change anything good or bad. In fact the bike never really had much bog anyway.

Could this be jetting related? I ride in the North Texas area and it's hot now. My bike doesn't do this when it's cooler.

Any ideas?

Oops, I might mention that the bike is an 01' 426.

Hot, sputter. Cool, no sputter. Only on low end. Lean out fuel screw a little. If that doesn't do it, go one smaller on pilot.

Good luck,


Thanx Mark,

I'll try that this after noon.

Just chk also the air screw did not fall out as mine did, Same symptoms, when I went to adjust, walla OOOOKKKK no screw...

I had some serious problems with mine doing that also, got a Kouba t-handle screw to be able to adjust on the fly, but I think my main problem was that the air boots between the carb and the head were loose, try to turn your carb with your hands and see if it will move, mine was sputtering like crazy till I found out that the boots were loose, tightened em up, no more sputtering!! Good luck Frank

Hey Kirtwell, I recently just posted a similar topic, my 98 wasbasically doing the same thing. I had adjusted the fuel screw for colder weather at the end of last year, and now that it is hot again the bike started to crap out on me...I turned the fuel screw out 1/4 of a turn and cleaned the diaphram out really good...BAM!!! runs like a dream once again. Hope you get it figured out soon, so you can come to Duncan and rip it up!!!!!! Later man


You said you turned the screw OUT 1/4 turn?

I thought that would make it richer...Heck...i'm turning it the wrong way :)

Turning it out DOES make it richer. Lean in, rich out, lean in, rich out, lean in, rich out! :)

Kirtwell, Hey man, Did you try to turn it in like Mark suggested? Im not sure what to recommend on lean or rich, all I know is mine needed to be turned out for the hot weather...and I know it is hot where you are too sooo, its worth a try, also I might add that mine is at all stock jetting and needle settings, if that makes a difference. We are going to have to get together and either get you here to ride the Ducnan track, or Im going to meet you at the Nacona track and do some riding!!! Catch you later man, hope you get it running right soon!!!

Ok It's fixed now.... :D

Don't give me any crap for this but it turned out to be 2 things I did wrong...

1. The seal between the carb and the airbox was loose...thanx FASTFRANK

2. The air fuel screw was all the way in :D I thought I was screwing it out the last time I adjusted it but I guess I wasn't...Anyway...after turning it out 1 1/2 turns was purring like a kitten....

Just a little embarrassing...but my ride is running great so :)

Cya out there.

It's nice to know what fixed it. Thanks.

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