Backfiring (After installing full exhaust + K&N Air Filter) - 600RR.net
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post #1 of 6 (permalink) Old 07-02-2011, 01:59 PM Thread Starter
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Backfiring (After installing full exhaust + K&N Air Filter)

Hey Everyone,

I have a question that I'm posting for a friend. It isn't actually a CBR question, since his bike is an R6 but I think it applies to all bikes.

We installed a Yoshimura R-55 Full Exhaust, along with a K&N High Flow Air Filter. He then got his bike tuned professionally.

Now my question is, his bike still backfires at high RPMS right when he shifts gears. Is this normal behavior for a bike with these modifications, even after a tune? And how damaging is the backfiring to his bike?

I figure a lot of you have similar modifications on your bike, and I'm wondering if all of you experience backfiring, even after you get it tuned.

Thanks,

Cruz

Last edited by RnAoDm; 07-02-2011 at 02:34 PM.
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post #2 of 6 (permalink) Old 07-02-2011, 02:01 PM
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A friend of mine still has backfiring on his 04 R6 after a "professional" tune. It is not a huge concern if it comes from the exhaust after a shift. It means it's running rich, and the unburned gasses are being ignited when they hit oxygen. Far less of a concern than running lean. many bikes will do this, watch IOM TT in slow motion and you will see.

If his air filter is becoming moistened with gasoline take it back & get it retuned ASAP.

Fast forward to 2:40


Current bikes:
2004 CBR600RR (daily rider, to be raced)
2006 CRF450R
1973 CG150 (off road, future restoration project)
1971 CB100 (being restored)
2006 BWS50 Zuma
Bikes of my (recent) past:
2004 Honda Ruckus, completely built, 55mph on the flats, 60 downhill and/or drafting
2007 Kawasaki Ninja 250
2004 Yamaha R6

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Last edited by michaelwood; 07-02-2011 at 02:06 PM.
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post #3 of 6 (permalink) Old 07-02-2011, 02:04 PM
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backfiring is not damaging at all, most of the time

sounds liek the tune has the bike dumping a lot of fuel into the motor, and when he lets off the throttle for a split second to shift, there a bunch of unburnt fuel .... when it mixes with enough oxygen (at the end of the esxhaust can) it burns/blows up, this a back fire.



you cna also get a lean backfire ... but i wouldnt expect this if the tuner was half way copetent


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post #4 of 6 (permalink) Old 07-02-2011, 04:40 PM
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It's a good thing, at night flames shoot out of his exhaust! (if he deleted the cat)
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post #5 of 6 (permalink) Old 07-02-2011, 05:02 PM
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Can exhaust baffling be hurt by fuel? If you are back firing a lot will it prematurely wear the muffler?
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post #6 of 6 (permalink) Old 07-02-2011, 05:10 PM
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Quote:
Originally Posted by foxx_mma View Post
Can exhaust baffling be hurt by fuel? If you are back firing a lot will it prematurely wear the muffler?
i doubt it, fiberglass is fairly resiliant...


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Flushmounts
fender eliminator
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