Backfiring...

**kevfromcoro** · 29th May 2009, 15:54

Originally Posted by gwigs

You could also have a small exhaust leak...which would cause some backfiring when throttling off..block off the can and listen for any leaks...

you are on to it,, exhaust leak will do it.....
been thinking about this all day

**MSTRS:Me** · 29th May 2009, 15:55

Originally Posted by Cheshire Cat

OH! ok

lol

I see you missed my subsequent post....
< followed by > and with sufficient characters in between, but without the gaps, counts towards post characters, but doesn't show in the displayed post.

**Cheshire Cat** · 29th May 2009, 15:57

Originally Posted by XP@

Before you pay out for a mechanic:
Try tightening all bolts on your exhaust and check for holes in the pipes.

Ok will do!

Thanks!

**samgab** · 29th May 2009, 16:57

Only one other thing I can think of that could possibly cause backfiring, and you could fix by yourself if it is the reason:
Choke left on the whole time.
Probably a silly question, but do you know where the choke lever is and made sure it's off?
Unlikely, but I've heard of sillier things.

**Str8 Jacket** · 29th May 2009, 17:07

See, if it was one of my 2smokers, I would be checking the spark plug... 4 strokes are *so* complicated

**Cheshire Cat** · 29th May 2009, 17:26

Originally Posted by samgab

Only one other thing I can think of that could possibly cause backfiring, and you could fix by yourself if it is the reason:
Choke left on the whole time.
Probably a silly question, but do you know where the choke lever is and made sure it's off?
Unlikely, but I've heard of sillier things.

HAHA yes I do know where the choke is and I hardly ever use it.

**MSTRS:Me** · 29th May 2009, 17:50

I doubt that the choke has anything to do with it. Backfiring is usually caused by a lean mixture. There can be many reasons.however.
Slight blockage in a carburetor jet.
No air filter, or a big hole in it.
Loose inlet manifold.
Loose header pipe.
Lack of back pressure in the exhaust due to above, or to a missing baffle/overly-free flow.
Something wrong in the firing of the spark plug. Or timing. With 'blackbox ignition systems' (no points) that would be rare.
Then there is the delayed detonation form, where unburnt fuel is released into the exhaust and then ignites due to heat in the pipe.

**samgab** · 3rd June 2009, 00:38

Originally Posted by Cheshire Cat

Lately I've noticed my bike is backfiring alot

when I'm changing gear and when I'm riding at 50 and 70k's. I don't like it to scream so I stay in 5th till about 60k.....could I be in too higher gear? Or is it tuning? Or is this just normal? haha

Help....

So did you get anywhere with getting this sorted?
And whose is the hornet in the background of the pics of the CBR?

**Cheshire Cat** · 3rd June 2009, 10:53

Originally Posted by samgab

So did you get anywhere with getting this sorted?
And whose is the hornet in the background of the pics of the CBR?

Yes! The pipe beside the petrol tank cap has a kink in it so the watcer has been building up.We think thats the problem anyway.If not we'll check the spark plug and if its not that then......

Thats Goblins hornet.

**rosie631** · 3rd June 2009, 11:14

Could be fouled plugs. When I first got mine it had a shit battery. Had to jumpstart it and each time I did by the time I got seat back on etc it had fouled the plugs. Used to backfire like nothing on earth when that happened.

**CookMySock** · 3rd June 2009, 11:40

Originally Posted by gwigs

You could also have a small exhaust leak...which would cause some backfiring when throttling off..block off the can and listen for any leaks...

Agreed.

Originally Posted by XP@

Before you pay out for a mechanic:
Try tightening all bolts on your exhaust and check for holes in the pipes.

Agreed.

Exhaust leaks are a big cause of backfiring.

People in the Rotorua, Tauranga, and Whakatane areas - remember I have somewhat of a workshop here, and plenty of experience with all things mechanical, plus a welder and other bits and pieces, so I can show you how to do simple things for yourself.

Steve

**Cheshire Cat** · 3rd June 2009, 15:46

Took the tank off today and straightened that pipe.Looks like some one put it back togther wrong

and we found water and rust in the tank

will be cleaning that out soon.

**Max Preload** · 5th June 2009, 12:54

Originally Posted by Cheshire Cat

...and we found water and rust in the tank

will be cleaning that out soon.

Don't forget to do the carb too - the float bowl will be full of water.

As for the 'backfire' if it's more like a burble on overrun rather than an actual full on *BANG* it's likely just an exhaust leak.

**Cheshire Cat** · 5th June 2009, 16:14

Originally Posted by Max Preload

Don't forget to do the carb too - the float bowl will be full of water.

As for the 'backfire' if it's more like a burble on overrun rather than an actual full on *BANG* it's likely just an exhaust leak.

Yes, must stop being so lazy and do that every morning lol

ok. I'll check the exhaust too.