Sign in to follow this  
Followers 0
shanet1975

Backfires when decelerating (sp)???

12 posts in this topic

Hello,

You have all been incredibly helpful with me getting my 01 YZ426 starting much easier. It was the plug after all. Talk about a pain to change that out. Well onto issue # 2. I've noticed that it takes a little to rev down to idle after I let off the gas and when decelerating she seems to backfire. I've heard that this could be the pilot screw????No manual with bike. Can someone tell me if this sounds right and if so, how to go about resolving.....?

Thanks for your time...

Share this post


Link to post
Share on other sites

Sounds like you are a tad lean on the fuel screw. There is a flat head screw in the bottom of the carb, recessed in a hole about in the middle of the carb. It controls fuel so "IN" or clockwise to lean, "OUT" or counter clockwise to richen. Turn yours using 1/8 turn increments till the idle returns to normal right after you close throttle, this should also rid the backfire problems on decel. Dont turn OUT more than 2.5 turns total. If you have to go more turns, its time to go up one size on the pilot jet.

NOTE: bumbling/burping on decel is not necessarily bad. You just want to avoid loud backfires

Share this post


Link to post
Share on other sites

Thank you so much. I will look for that tonight when I get home. Should I go all the way in with it, then back out so I know how many turns it's been, or 2.5 turns from where it is?

Thanks again.........

Share this post


Link to post
Share on other sites

Yes, turn all the way in and then count the turns out as you go.....

Stock setting is somewhere between ~1.5-2.0 turns out

Share this post


Link to post
Share on other sites

After you accomplish the whirl try to do a search on backfires. You will gleam a whole cornucopia of information.

Share this post


Link to post
Share on other sites

The spell check tab on the bottom of your message will work too :naughty:

Share this post


Link to post
Share on other sites

Haven't had time to give her her a whirl and probably won't tonight. Thank you all for the input and laughs. I'll be taking my daughter out on her 90 atv this weekend so I should have some time to get her just right. Hopefully.

Thanks again....

Share this post


Link to post
Share on other sites

This is good information. My 426 had some heavy back fires. I put a quieter Yosh silencer into the exhaust canister, and that helped quite a bit. Enough that that was as far as I wanted to go, but if it's just a screw turn? Hell, shucks, I'm always ready to screw. :naughty:

Share this post


Link to post
Share on other sites

Do a search like the other member said. Check that all exhaust connections are tight without leaks.

Share this post


Link to post
Share on other sites

The best way to adjust the fuel screw is by doing it under heavy deceleration. Ride it around on the track until its good and warmed up and then adjust it until it just starts to brumble and almost pop when you are having to really hammer the brakes and pull the speed down going into a tight corner from a long run on the track.

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