HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
meangreen75

constant backfiring

9 posts in this topic

I have an 00' YZ 426 and it's been backfiring for the last couple of months. I didn't think about too much on the track but I noticed it last time out. If anyone has had this problem and fixed it let me know what ya did. Thanks.

Share this post


Link to post
Share on other sites

Try adjusting the fuel screw on the bottom of the carburetor out. With colder weather, your bike will tend to run lean. By adjusting the fuel screw out it'll give it a little more fuel. The screw is recessed in a little hole, I use a apex tip flat blade screwdriver to reach mine. Good luck,

Pat

Share this post


Link to post
Share on other sites

Hey guys, is it possible he may have an air leak in the exhaust somewhere?

I read about this once but can't remember if this was the case or not....

Anyway, good luck!

Share this post


Link to post
Share on other sites

Its more likely that an exhaust leak is causing your recent backfire than a jetting issue. You might want to pop the head pipe off and look for the leak. You can use a little red silicone if neebe to seal her up good. Its improbable that you would get a backfire from the muffler junction if it was leaking so look at the headpipe to cylinder area. A leak will look like a dark spot on the sealing face of the flange when disassembled. Good luck

Share this post


Link to post
Share on other sites

Its more likely that an exhaust leak is causing your recent backfire than a jetting issue. You might want to pop the head pipe off and look for the leak. You can use a little red silicone if neebe to seal her up good. Its improbable that you would get a backfire from the muffler junction if it was leaking so look at the headpipe to cylinder area. A leak will look like a dark spot on the sealing face of the flange when disassembled. Good luck

Share this post


Link to post
Share on other sites

I had a similar backfiring issue over a year ago. After chasing this gremlin for a while, I found an air leak where the airbox connects to the carburetor adaptor. The adaptor has two bushings that the Allen head bolts nug against. One of the bushings lost its integrity and slipped over the head of the Allen bolt and left a tiny gap where dirty air was being sucked in. That was a difficult leak to find. I used an oxygen bottle to find it.

Share this post


Link to post
Share on other sites

If the fuel screw and cleaning the carb don't do it then be sure to check your valves. I've seen it mentioned that overly tight exhaust valves can contribute to this.

Share this post


Link to post
Share on other sites

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
Sign in to follow this  
Followers 0