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Hi guys.Greetings from TuRKEY.I saw your forums a day ago.Yo guys have brilliant ideas and solutions.My problem about exhaust backfires.I have Yamaha R25.I'm using full system akrapovic exhaust.I don't want to back fires.How can i do this?
 

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any tuning after the exhaust installation? i am new to motorcycle but i know about cars.... backfire could be related to incorrect fuel, spark plugs, incorrect tuning, remove of the cat ... and worst case scenario like valve timing...

you will heard from any other experienced rider in here about your issue...
 

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The reason you have backfire is because your AIS system is pushing fresh oxygen into the exhaust and as the exhaust is quite hot, it ignites the excess fuel that is left over from combustion.

Normally that additional oxygen (from air) reacts with the gases in the catalytic converter to produce less harmful gases (and water).

Since you have no cat, you just backfire.

You can install a block off plate and even take the AIS out of the bike when you do that. This is what I did, and yes, it will remove 99% of backfire. I still occasionally get a pop when shifting gears however I'm getting mine tuned tomorrow so shall see what happens.


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From my experience even a stock muffler will back fire. You hear it much less though because a stock exhaust is much quieter than most new aftermarket exhausts.

I had a 2 bros full exhaust on another bike and when first installed it backfired/popped a lot. Natural thing to do was block off where air is introduced to reduce the popping. That helped a bit but it still did it on decel. You need to make sure you have no leaks. As mentioned, reintroduction of air is what will cause this. Someone on the 650 forums (Cliff Randal) made a map for the 650 and passed that map around. That really helped out a lot of our bikes, all while smoothening it out as well.
 
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