Backfiring

T1z3R · World Chat Champion Joined: 23 Oct 2005 Karma :

i think its caused by unburnt fuel?

happens on my bike...more than i'd like to be honest but usually just before 7krpm just before the powerband in any gear above second..
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iCraig · World Chat Champion Joined: 05 Jun 2004 Karma :

It happens cos air is getting into your exhausts at some point, maybe your downpipes are leaking from where the gaskets are.

My bike does it too.

Also talking of back firing I discovered today, that if I switch off the ignition at the killswitch, and turn the bike over and then switch it back on it makes an almighty massive backfire!

Davo · Davo To The Rescue! Joined: 05 Apr 2004 Karma :

My R6 used to pop like a bitch on the over run whilst on track. Shouldn't worry about it too much.

Cog Head · Could Be A Chat Bot Joined: 21 Oct 2005 Karma :

You wana do it on purpose in the middle of brum and watch as all the black people dive toward the ground and the white people just stand there thinking WTF... Twisted Evil

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tatters · Exxon Valdez Joined: 05 Jan 2004 Karma :

I reckon its those 33bhp restrictors Wink

Better take them out before you get 0wned by a superdream.
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Cog Head · Could Be A Chat Bot Joined: 21 Oct 2005 Karma :

doggone · World Chat Champion Joined: 20 May 2004 Karma :

It shouldn't do it really - it's a symptom something isn't right as suggested above.
May get worse and develop into a starting problem.
In theory it might damage your valves I suppose.
Another risk is startling horses/dogs/sheep out of town - not funny if a horse jumps sideways and hits you - have seen this as the backfire will happen when you shut the throttle approaching the animals.

riichy · World Chat Champion Joined: 12 Apr 2005 Karma :

i have a race can on mine and it pops like a bit#h.....

most bike with race can get it sounds ace and i dont think it dose any damage...i hope Rolling Eyes

...

but as long as its not relly loud ones should be fine Thumbs Up

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.......... PLOD ............ zx636 2004

Dom_ · Points Mean Prizes Joined: 02 Aug 2004 Karma :

Argh! It's not a backfire. Sounds like you have a small airleak, the cold air is drawn into the exhaust when you back off the throttle and expands in the hot exhaust and pops. (I think.)

instigator · Super Spammer Joined: 19 Oct 2004 Karma :

Should ride my vtr. Laughing

The er5 was worse for it infact, but it sounded MAAZING...pop pop pop pop everytime you went under some engine braking. Very Happy

I don't think it's a problem unless it's excessive.

numark1 · Scared of girls Joined: 10 May 2004 Karma :

I had it major on my zx6r. It was cool, accelerate hard, make peoples ears bleed then crackle off into the distance. Cool

Andy C · Tree Seeking Missile Joined: 26 Apr 2005 Karma :

my bike does it, as a V-twin and race can happens a lot but not as much as i thought it would, never get big backfires,

the other day i started it and it started on second press with a MASSIVE backfire and scared the sh*t out of me as was still in my passage down side of my house!!! Shocked

i dont think it does any damage, is just unburnt feul or air bubbles in exhaust, somthing like that Thumbs Up

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dotti · Scooby Slapper Joined: 18 Dec 2004 Karma :

The GN250 used to do that all the time, until I increased the Octane of the fuel I was using from 91 octane to 95 or 98 (depending where I fill up).

Changing the spark plug also helped. I can only assume if the spark plug was dirty and not firing properly, some of the fuel was still unburnt when the exhaust valves opened up.
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mattsmith95 · Traffic Copper Joined: 03 Oct 2004 Karma :

Wave2k · G's Stalker Joined: 06 Apr 2004 Karma :

i dont think it does any good to your valves.
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EuropeanNC30R... · Gay Hairdresser Joined: 20 Jun 2002 Karma :

I've heard of it bending exhaust valves, saying that I still do them occasionally. As long as you're not doing them like a bastard off the kill switch everyday you should be ok I think.

Also they tend to burn your exhaust baffles, so you might find it getting louder over time.

Knowlsey · Scooby Slapper Joined: 07 Apr 2005 Karma :

I'd worry more about the exhaust than the valves, its due unburnt fuel, and because there is a lot of air in there you get a big bang, and it has blown cans off and holes in exhausts

jayluvmito · Crazy Courier Joined: 15 May 2004 Karma :

i'd worry more about valves tbh. more expensive, more likely to go wrong..
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SoND · World Chat Champion Joined: 10 Jul 2005 Karma :

I've noticed my friends CBR125 backfiring sometimes when we're riding about. At night you would see a small blue flash at the end of the can.

He has a full micron system so I'm guessing it's just that. There is a seal broken where it bolts to the downpipes, he's been told it can't be fixed and it happens on a lot of Microns.
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