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colorado kx 450 backfire

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So I was wondering if my bikes air filter could cause back fire like if its not getting enough air and too much gas or something it's just backfireing also if it could be my exhaust I have a big gun eco so please just leave information on why my bike could be backfireing and it is a 2011 Kx450f

Edited by Raid Casper

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55 minutes ago, kxlubber said:

Could it be old packing in your muffler?

Possibly I mean my exhaust hole at the end is really really big so it could just be that

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4 minutes ago, Raid Casper said:

Possibly I mean my exhaust hole at the end is really really big so it could just be that

It's also pretty loud like way louder than the stock exhaust so

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24 minutes ago, Raid Casper said:

Possibly I mean my exhaust hole at the end is really really big so it could just be that

I don't have a spark arrestor 

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Backfiring is often a symptom of an over-lean fuel mixture. This could be caused by an air leak in the intake tract or an exhaust modification that has too little backpressure. Most bikes require a re-jetting when you put a performance exhaust on them -- or when you remove internals in the factory muffler. Freer-flowing exhausts cause lean conditions.

Check all the connections on the intake side to make sure there's not an air leak. If no leak is found, make sure your exhaust creates the proper amount of backpressure. If you ride on public land you should always use a spark arrestor. 

An acquaintence recently showed up to ride at Ramp;art and was checked in the parking lot by the FS for his spark arrestor. It was missing and he was not ticketed -- but told to go get an arrestor/muffler by the ranger. If he'd been stopped while on the trail, it would have been a $100 fine.

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1 hour ago, mrgem said:

Backfiring is often a symptom of an over-lean fuel mixture. This could be caused by an air leak in the intake tract or an exhaust modification that has too little backpressure. Most bikes require a re-jetting when you put a performance exhaust on them -- or when you remove internals in the factory muffler. Freer-flowing exhausts cause lean conditions.

Check all the connections on the intake side to make sure there's not an air leak. If no leak is found, make sure your exhaust creates the proper amount of backpressure. If you ride on public land you should always use a spark arrestor. 

An acquaintence recently showed up to ride at Ramp;art and was checked in the parking lot by the FS for his spark arrestor. It was missing and he was not ticketed -- but told to go get an arrestor/muffler by the ranger. If he'd been stopped while on the trail, it would have been a $100 fine.

There was a rip in my air filter if that could be a problem causing backfireing

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1 hour ago, mrgem said:

Backfiring is often a symptom of an over-lean fuel mixture. This could be caused by an air leak in the intake tract or an exhaust modification that has too little backpressure. Most bikes require a re-jetting when you put a performance exhaust on them -- or when you remove internals in the factory muffler. Freer-flowing exhausts cause lean conditions.

Check all the connections on the intake side to make sure there's not an air leak. If no leak is found, make sure your exhaust creates the proper amount of backpressure. If you ride on public land you should always use a spark arrestor. 

An acquaintence recently showed up to ride at Ramp;art and was checked in the parking lot by the FS for his spark arrestor. It was missing and he was not ticketed -- but told to go get an arrestor/muffler by the ranger. If he'd been stopped while on the trail, it would have been a $100 fine.

Also I don't think I have jets it's fuel injected

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Of course. My mistake. I'm an old guy who rides an old (carburetted) bike. Just slapped my forehead.

That acknowledged, a too-lean mixture could still be the problem. In theory, the computer should be able to compensate for some lean conditions, but not all. The air filter rip might be causing it and installing a new one would be an easy place to start.

Does it backfire all the time, or just under certain conditions? A lot of later model bikes seem to do it on closed-throttle deceleration. 

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1 hour ago, mrgem said:

Of course. My mistake. I'm an old guy who rides an old (carburetted) bike. Just slapped my forehead.

That acknowledged, a too-lean mixture could still be the problem. In theory, the computer should be able to compensate for some lean conditions, but not all. The air filter rip might be causing it and installing a new one would be an easy place to start.

Does it backfire all the time, or just under certain conditions? A lot of later model bikes seem to do it on closed-throttle deceleration. 

When it's in neutral and 1st about half throttle and after I get off the gas after full throttle on deceleration but it only will do it every once in a while

Edited by Raid Casper

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read up on deceleration pop....probably what you are experiencing with an aftermarket muffler.  Not super familiar with the Kawi fuel injection system, but I assume you can download other fuel/ignition maps.  I know that JD Jetting probably sells equipment that overlays or adds on to the factory fuel injection mapping.

Your likely bigger problem was the rip in the air filter that was allowing unfiltered dirt to get into the engine.

Take a look at the specific KX450F forum here at TT.  They probably would be able to provide you with better guidance:

https://thumpertalk.com/forums/forum/70-kx450f/

 

 

 

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So also I haven't messed with the feul screw so that my problem but I got a new air filter and bike sounds a lot better 

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So also I haven't messed with the feul screw so that my problem but I got a new air filter and bike sounds a lot better 
Some Decel popping on the kx450f is normal. Things you can check that if it continues is where the header meets the engine there is a brass gasket that might need replaced. Packing in the muffler like what has been mentioned should be replaced you will be surprised how much this helps. Last one is the timing chain I know doesn't make sense but when this gets old and starts kinking it can cause popping as well.
But some popping is normal and you will probably never get rid of all Decel popping on these bikes.

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