Hey how's it going ! So I got an 2006 klx 250 nice bike good shape but the thing is I'm thinking about getting the big gun Evo r exhaust system. Has anybody installed this exhaust on a klx 250 of similar year?? And after installation how does the jetting work I'm kinda lost with that part. All of this comes from my current exhaust backfiring when letting go throttle. Thanks for the help. Shoots mahalo!!

 

That's almost certainly not backfiring, which is very bad and would have probably caused damage by now. Backfiring is the engine firing back into the intake. BAD

It is almost certainly what is called deceleration pop, or decel pop. You'll also hear other names for it. It is unburnt fuel igniting in the exhaust. It is perfectly normal, and you would hear it on a lot of vehicles if they didn't have restrictive mufflers that mask it. If you don't like it, you can tune it out. But changing to another muffler won't help, unless you put the stock back on. I'd suggest that you start searching here for decel pop. You'll find better descriptions by more knowledgable than me, and all the info you need to tune it out if you want.

 

Here is a recent thread. Read it all, especially klxster comments which worked for me and others. There must be dozens of other threads on this subject also. Lots to learn!

https://www.kawasakiforums.com/forum/klx-250s-71/after-market-fuel-mixture-screws-45820/

You can find more tuning advice than you can handle on this board, too. Just roll up your sleeves and dig in.

 

Stefan, you have a fault with your carb and/or your exhaust connections. Put that Big Gun system on, without fixing your problem, and your backfiring will wake the dead..

I know nothing of your bike - that being said, if you are very lucky, simply backing out your fuel screw to 3.5 turns out will solve your backfiring problem..

 

Hoooly cow !!! Yeah!! thanks you guys for all that great infoo still haven't done nothing just meditating all the possibilities for now haha.so yeah the poping sound I love it was concerned about it being backfire cause i don't know if it's been jetted or ajusted to aftermarket exhaust setup. Ive been
thinking about connecting the stock exhaust with what I believe is a big gun Evo x (I know it's big gun for sure previous owner don't remember what model) anybody have that kinda setup. I could cut stock header and weld an adapter cause this big gun header has a big dent and heats up pretty gnarly, any thoughts??

Yeah so if it were something to do with the carbs like one o u guys said how do I find out ?? I should probably check the carbs cause it's an old bike 06 so any tips on that kinda stuff ? Shoots man thanks alot ! Enjoy da ride mahalo braddaz

 

Big gun. model : Evo x????

Big dent in header can it cause excess heat???

 

Maybe, maybe not, but I guarantee you that one cut the flow in half. I'd cut the pipe with a hacksaw in the middle of the dent, also make a mark so you know how it needs to line up, then carefully tap out the dent with a ball peen hammer using whatever possible to get it to round out again. Then weld it back together.

Anyone got any better ideas please contribute.

I had to do that with an expansion chamber head pipe on my Kaw 400 S3 triple. I bumped a curb. I also had to do it in the middle of a cone on my Suzuki TM125 motocrosser, when I flattened the middle going over a railroad track. That one totally destroyed the power of the engine.

 

 

Might work. Expansion chamber cones are a lot thinner though.