Bike sputtering

11 replies to this topic
  • Kirtwell

Posted July 20, 2002 - 02:39 AM


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?

  • Kirtwell

Posted July 20, 2002 - 02:40 AM


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

  • Mark_Cantrell

Posted July 20, 2002 - 03:43 AM


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,

  • Kirtwell

Posted July 20, 2002 - 04:48 AM


Thanx Mark,
I'll try that this after noon.

  • John_Lorenz

Posted July 20, 2002 - 06:06 AM


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


Posted July 22, 2002 - 06:18 AM


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

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • m2g4b

Posted July 22, 2002 - 07:26 AM


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

  • Kirtwell

Posted July 23, 2002 - 07:38 AM


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 :)

  • skthom2320

Posted July 23, 2002 - 07:51 AM


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

  • m2g4b

Posted July 23, 2002 - 10:22 AM


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!!!

  • Kirtwell

Posted July 24, 2002 - 07:02 AM


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.

  • skthom2320

Posted July 24, 2002 - 12:03 PM


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

Related Content


Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

Wilson the Blue Privateer by jetfuel

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  50 replies

James Stewart back on a YZ450F by YamaLink

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On Yesterday, 06:20 PM

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.