2008 YZ450F tech issue

I went riding today. Interresting issue. My bike has plenty of power, but when I am under throttle and going through whoops, my bike studders. It's almost like you shut the fuel off and it's starving for gas. Don't know if the float pin is getting stuck or if its an issue with the ignition. Has this happened to anyone else? Thaks Wes:banghead:

I went riding today. Interresting issue. My bike has plenty of power, but when I am under throttle and going through whoops, my bike studders. It's almost like you shut the fuel off and it's starving for gas. Don't know if the float pin is getting stuck or if its an issue with the ignition. Has this happened to anyone else? Thaks Wes:banghead:

I have this too on my 426 and cant help but think that its just yamabog. I have never experimented with accelerator pump covers but people say that they cure this.

Jetting is spot on, R&D Powerbowl, no bog, pipe, good 100 octane fuel. 13 hours on engine. it just started today. I'm gonna pull the carb and check it out.

Are you sure you aren't hitting the rev limiter when the wheel comes off the ground between whoops and is free spinning?

Jetting is spot on, R&D Powerbowl, no bog, pipe, good 100 octane fuel. 13 hours on engine. it just started today. I'm gonna pull the carb and check it out.

wow, you have all the upgrades already. Maybe a problem with float needle like you said

Update: have you checked your gas cap vent? I just remembered that when I went to jawbone canyon last, my vent cap got plugged and was not letting air into the tank causing the carb to not get enough fuel. Just a thought.

Are you sure you aren't hitting the rev limiter when the wheel comes off the ground between whoops and is free spinning?

You know, I didn't think of that. I will take notice. Thanks again.

Sounds like a lean condition or a faulty tps. My bike was stutering and I bumped up the main jet from a 162 to a 165 and it went away. Also, Ive read in the jetting section that disconecting the tps may solve the stutter if the TPS is bad.

If it is only doing it in whoops, try hitting them in a gear higher and see if it doesn't do it quite as bad. If so, then it is the rev limiter, if it doesn't then it could be an actual mechanical issue related to pounding (loose wire in ignition system, low float level causing fuel to slosh, or some other issue).

wow, you have all the upgrades already. Maybe a problem with float needle like you said

Update: have you checked your gas cap vent? I just remembered that when I went to jawbone canyon last, my vent cap got plugged and was not letting air into the tank causing the carb to not get enough fuel. Just a thought.

Yes, that was the first thing I checked. I pulled it off and blew through it. Thank you for the ideas. It is frustrating.

If it is only doing it in whoops, try hitting them in a gear higher and see if it doesn't do it quite as bad. If so, then it is the rev limiter, if it doesn't then it could be an actual mechanical issue related to pounding (loose wire in ignition system, low float level causing fuel to slosh, or some other issue).

We are on the same page! I appreciate you response!:thumbsup:

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now