2009 yz250f backfiring
- Thread starter wipe out
- Start date
AreWeThereYet
Active VIP Member
Check for exhaust header cracks, might be running lean,.. what does the plug look like?
FossY
Active VIP Member
does it still have the hotstart plunger ? cause if thats stuck or open itll do that
airbox boot leak could also cause it
airbox boot leak could also cause it
TheMuffinMan
Active VIP Member
Air leak for sure. As said check the boots on either side of the carb for leaks. Then pull the exhaust header off and check that the copper crush washer is sealing properly (they're cheap so you might want to throw on a new one for good measure), and make sure you tighten down the two flange bolts evenly when you remount it. Then check that the muffler/header junction clamp is tight. Lastly check that your fuel screw on the bottom of the carb isn't grossly out of adjustment or worse, missing completely; I've seen a few fall out. That should stop any air leaks.
suzuki_ryder
Active VIP Member
it cold outside right now and that bike will be running lean. you'll need to open your fuel screw, or bump up a size on the pilot if that doesn't cure it.
takethebounce
Active VIP Member
Decel backfire can be caused by a few things. I have a little on my KX that I have never gotten rid. These are race bikes afterall, with a large open pipe they will pull in a little air.
One way to see if its a lean condition is to see if it goes away when the choke is on.
As long as its not hard to start and not popping on acceleration its generally an easy fix.
If you don't have the owners manual with it, try and get one. In it should be base line settings for your carb. You will want to adjust your fuel screw and possibly the pilot jet. If you are using the bike for just general riding a larger pilot can help.
For example, if you have a 40 pilot, go to a 42 and turn your fuel screw out a 1/4 turn.
But yeah check your exhaust as well...most likely carb set up.
One way to see if its a lean condition is to see if it goes away when the choke is on.
As long as its not hard to start and not popping on acceleration its generally an easy fix.
If you don't have the owners manual with it, try and get one. In it should be base line settings for your carb. You will want to adjust your fuel screw and possibly the pilot jet. If you are using the bike for just general riding a larger pilot can help.
For example, if you have a 40 pilot, go to a 42 and turn your fuel screw out a 1/4 turn.
But yeah check your exhaust as well...most likely carb set up.
- Thread starter
- #7
Similar threads
