constant backfiring



8 replies to this topic
  • meangreen75

Posted January 17, 2002 - 07:17 PM

#1

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.

  • PK

Posted January 17, 2002 - 07:43 PM

#2

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

  • Ga426owner

Posted January 18, 2002 - 05:39 AM

#3

adjust your pilot screw.......Kouba works great for this

  • JDM

Posted January 18, 2002 - 06:01 AM

#4

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!

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  • Shawn_Mc

Posted January 18, 2002 - 09:33 AM

#5

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

  • Shawn_Mc

Posted January 18, 2002 - 09:36 AM

#6

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

  • john.hilton@cape.k12.de.u

Posted January 18, 2002 - 09:37 AM

#7

Shawn Mc

Did you get your Thunder Alley Pipe yet?

Or am I thinking of someone else? If you did get one, how do you like it?

Did it take any of the low-end away?

Thanks, John

  • Boit

Posted January 18, 2002 - 08:44 PM

#8

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.

  • sirthumpalot

Posted January 19, 2002 - 02:36 PM

#9

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.





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