NASTY BACKFIRE ON START UP
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NASTY BACKFIRE ON START UP
Hi All,
Am wondering if anyone has a problem with their rex letting off a really nasty backfire when they press the starter after being stationary over night??????
I have 2 rex's, one with a k&n filter and megacycle round exhaust pipes its my road bike and does a huge backfire every morning much to my neighbours disgust at 6:00 am mon to fri, the other being my track bike,when it used to be my road bike it suffered the same problem, the set up was the same except for the cans, they were megacycle oval cans.
I've checked the carbs on both bikes and have found no wear to the emulsion tubes, even after a tune up they still do they backfire thing
Any clues would be greatly appreciated.
Cheers, Mick
Am wondering if anyone has a problem with their rex letting off a really nasty backfire when they press the starter after being stationary over night??????
I have 2 rex's, one with a k&n filter and megacycle round exhaust pipes its my road bike and does a huge backfire every morning much to my neighbours disgust at 6:00 am mon to fri, the other being my track bike,when it used to be my road bike it suffered the same problem, the set up was the same except for the cans, they were megacycle oval cans.
I've checked the carbs on both bikes and have found no wear to the emulsion tubes, even after a tune up they still do they backfire thing
Any clues would be greatly appreciated.
Cheers, Mick
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Add mine to the list that does it occasionally - moreso since I've had the Scorpions on (and with them on it's stupidly loud!).
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Re: NASTY BACKFIRE ON START UP
I got it when i opened the airbox and put in K&N filter (and racecans)...mickjmag wrote:Hi All,
Am wondering if anyone has a problem with their rex letting off a really nasty backfire when they press the starter after being stationary over night??????
I have 2 rex's, one with a k&n filter and megacycle round exhaust pipes its my road bike and does a huge backfire every morning much to my neighbours disgust at 6:00 am mon to fri, the other being my track bike,when it used to be my road bike it suffered the same problem, the set up was the same except for the cans, they were megacycle oval cans.
I've checked the carbs on both bikes and have found no wear to the emulsion tubes, even after a tune up they still do they backfire thing
Any clues would be greatly appreciated.
Cheers, Mick
Never gets it now with the keihin FCR´s....wich is nice because people was twisting their necks so it MUST have hurted!!
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I have a theory that this is caused by unburned fuel remaining in the pipes when the engine is turned off. As it's heavier than air it sits there undisturbed then when you start the bike there is sufficient hot gas exiting the engine to cause the backfire.
Anyway that's probably wrong, but that's my theory.
My bike does it, very rarely. My ZRX (also on a race can) used to do it very occasionally too.
Anyway that's probably wrong, but that's my theory.
My bike does it, very rarely. My ZRX (also on a race can) used to do it very occasionally too.
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I guess I classify a "backfire" as one through the carbs and anything out the other end a "pop"... Back through the carbs is not good (especially if you have oiled-foam filters that can ignite!), out the back is nothing to be worried about (unless you drive an old car with a rusty muffler that will eventually fall off if it happens often...). Muffler pops can be caused by a variety of things, excessive fuel build up which is fairly rare I think unless it was flooded. Open race type exhaust where deceleration allows a large volume of unspent gasses to grow untill the near the end a rush of O2 helps them ignite (my bike) or most commonly (on street bikes) a leak around the flanges in the front or mid section on joined pipes allowing oxygen to enter mid stream.
If you ever heard the first generation M1, they used an air induction system on the exhaust to help reduce engine braking... Sounded raucous for lack of a better word.
If you ever heard the first generation M1, they used an air induction system on the exhaust to help reduce engine braking... Sounded raucous for lack of a better word.
Max
(TaZ, tz250w)
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Olputt wrote
Actually, a friend of mine has a 2005 KX250F. When he was washing it one day, his 5 year old daughter stuck the running hose in the muffler when he wasn't watching. When he jumped on the kick starter it threw a leg out of bed.
Not pretty.
There is no need to wash the inside of the cans.I've also had issues starting it after washing - water in the cans.
Actually, a friend of mine has a 2005 KX250F. When he was washing it one day, his 5 year old daughter stuck the running hose in the muffler when he wasn't watching. When he jumped on the kick starter it threw a leg out of bed.
Not pretty.
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