Backfiring on newer KLR650 - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

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post #1 of 5 Old 07-26-2016, 07:56 AM Thread Starter
Join Date: Jul 2016
Location: Laurel, Maryland
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Backfiring on newer KLR650

I have the KLR650 which I bought Feb 2013 and only have 2024 miles without any mods yet when I let go of the gas it is backfiring? Are there any good sites that show me what I need to do? I was told that no cab cleaner is going to resolve this issue. I have seen something about turning some screw but I don't know for sure which one that is? Help Please! Oh, will I need to take the gas tank off to make this fix?
Thanks in advance for your time and help!
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post #2 of 5 Old 07-26-2016, 09:02 AM
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Some popping on decel is normal, perhaps especially so with a Gen 2 with the Air Injection System.

It's a lean pop, meaning the popping is because the closed-throttle mixture is a bit too lean.

There is a mod called the '22 cent mod' where you add a washer or two (#4 stainless washer) under the head of the needle to raise it, properly adjust the idle mixture, and drill a larger hole in the slide for improved throttle response. The slide drilling is not necessary if the only intent is to improve the mixture to reduce popping.

These videos may be of some help:

Look over some of the notes (particularly a response to Reiki Master on the second video) for discussion about the procedure for properly setting the idle mixture.


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Last edited by Tom Schmitz; 07-26-2016 at 09:27 AM.
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post #3 of 5 Old 07-26-2016, 09:50 AM
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Ironically I had more decel pop on the stock exhaust than I do with a slip on. Stock jetting. Every time I let off the throttle it would pop. I would assume it's completely normal. The AIS as said earlier also adds to the popping. The stock exhaust gets extremely hot with all its chambers, which I think adds to the popping.
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post #4 of 5 Old 07-26-2016, 10:45 AM
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Join Date: Aug 2009
Location: New Hampshire
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Popping or backfire?

When I got my KLR I tightened all nuts & bolts I could get to.
I missed the exhaust header nuts.
At about 9,000 miles, I had popping on decell. The header nuts were loose, and gasket was "toast"

After new gasket, and proper torque of the new nuts, it only pops slightly on major decell, like going down a long down hill.

Make sure you torque to proper spec.. They are acorn type nuts.
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post #5 of 5 Old 07-26-2016, 08:29 PM
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To me a backfire sounds like someone set off a very large fire cracker (cherry bomb) in the exhaust.

When I decelerate with a closed throttle I get a gentle burble, burble, burble. I like it and it is normal.
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