Backfiring...

[Cheshire Cat]

Lately I've noticed my bike is backfiring alot:confused: 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....:confused:

[MSTRS]

More info pls

[kevfromcoro]

No......... your bike shouldnt backfire.
its not normal...
sounds like it needs a tune up..
has it lost any power??
backfiring is usually to do with timing
more imfo would help.

[Cheshire Cat]

what do you want to know?

[MSTRS]

What sort of bike/engine would be a good start...

[Cheshire Cat]

No......... your bike shouldnt backfire.
its not normal...
sounds like it needs a tune up..
has it lost any power??
backfiring is usually to do with timing
more imfo would help.

haven't noticed any power loss....but it seems the revs are higher at 100ks now 8000rpm instead of 7500.



Info...05 CBR150R
changed the oil about 250kilometres ago
done 5300ks

Anything else?

[MSTRS]

haven't noticed any power loss....but it seems the revs are higher at 100ks now 8000rpm instead of 7500.



Info...05 CBR150R
changed the oil about 250kilometres ago
done 5300ks

Anything else?

Revs changing usually means the clutch is slipping or a sprocket has been changed. Nothing to do with the backfiring.
Does it backfire whilst riding at a steady speed, or when you roll off the throttle (to slow down).

[samgab]

FYI, a <a href="http://en.wikipedia.org/wiki/Back-fire">backfire</a> is when unburnt fuel/air ignites in the exhaust system (or intake system sometimes). Obviously this is not ideal for economy, because it means not all of the potential energy of the fuel has been used to drive the pistons in the combustion chamber.
It could be to do with the timing, or the carb adjustment. Valve clearances or something. Running too lean or too rich...
A good tune-up will likely solve it.

[Cheshire Cat]

Revs changing usually means the clutch is slipping or a sprocket has been changed. Nothing to do with the backfiring.
Does it backfire whilst riding at a steady speed, or when you roll off the throttle (to slow down).

Oh ok.Sprocket has been changed? explain please?:)

Both.

[Cheshire Cat]

FYI, a <a href="http://en.wikipedia.org/wiki/Back-fire">backfire</a> is when unburnt fuel/air ignites in the exhaust system (or intake system sometimes). Obviously this is not ideal for economy, because it means not all of the potential energy of the fuel has been used to drive the pistons in the combustion chamber.
It could be to do with the timing, or the carb adjustment. Valve clearances or something. Running too lean or too rich...
A good tune-up will likely solve it.

Ok.Where is the best place to get my bike tuned?(in rotorua or tauranga, I don't mind travelling:eek:)

[MSTRS]

Oh ok.Sprocket has been changed? explain please?:)

Both.
Your chain rides around a small sprocket at the engine end and a large one fixed to the back wheel. Those sprockets have X amount of teeth. If you wish to have better acceleration or higher cruising speed, then best way is to change one or both sprockets to Y amount of teeth, to change the gearing of the bike.

Can't recommend any particular shop, but a Honda dealer is probably best since your bike should still be inside the warranty period.

It might be something as simple as a loose baffle. But is more likely to be a faulty plug or fuel/air mixture.

[samgab]

Ok.Where is the best place to get my bike tuned?(in rotorua or tauranga, I don't mind travelling:eek:)

I'm not sure sorry, cos I'm not from that area, but you could try Rowlinson Honda for a start.
Also, does your bike have the standard (factory) exhaust system, do you know?
Does it backfire when you're decelerating, down a hill with high revs and the throttle closed?

[kevfromcoro]

Oh ok.Sprocket has been changed? explain please?:)

Both.

nah.. changing the drive sprocket wouldnt make it backfire....
iam sure someone will be along shortly with some good advice

[MSTRS]

Also, does your bike have the standard (factory) exhaust system, do you know?


If it's the one in her album, then it appears to have a non-standard can. When was this put on?

[samgab]

If it's the one in her album, then it appears to have a non-standard can. When was this put on?

Okay, just looked at the album picture. Yes, that's a bigger than standard, aftermarket, can. That could well be causing the backfiring, especially if the carb jets weren't changed at the same time... as they often aren't when someone puts a bigger can on a small bike to make it sound louder...
Solution could be a matter of new jets.
Again, a good motorcycle mechanic could confirm that.
Also, by looking at the state of the spark plug they could get an idea of the cause too. Wet, dry, black, brown, etc.

[Cheshire Cat]

If it's the one in her album, then it appears to have a non-standard can. When was this put on?

It was on there when I bought it...So I'm not sure:confused:

[Cheshire Cat]

I'm not sure sorry, cos I'm not from that area, but you could try Rowlinson Honda for a start.
Also, does your bike have the standard (factory) exhaust system, do you know?
Does it backfire when you're decelerating, down a hill with high revs and the throttle closed?

Yes it has done, but it mainly backfires in town...flat roads.

[Cheshire Cat]

Oh and I was told by some one that I should keep my tank full because condensation can build up inside the tank....?

[MSTRS]

Oh and I was told by some one that I should keep my tank full because condensation can build up inside the tank....?

Only if the bike is sitting round, particularly outside.
Otherwise, I wouldn't worry about it...except of course you will never run out!

[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...

[steve_t]

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...

+1
10 characters

[Cheshire Cat]

+1
10 characters

what?......

[MSTRS]

what?......

You are new...
This site has a 10 character minimum per post. "+1" means they agree, but it's not enough characters...

[nosebleed]

Only if the bike is sitting round, particularly outside.
Otherwise, I wouldn't worry about it...except of course you will never run out!

Or if you're filling it with Gull Force10

[MSTRS]

Or if you're filling it with Gull Force10

Huh? <fdjygfuygu>

[nosebleed]

Gull's Force10 is their Ethonal based "98"
Uses 10% Ethonal as an admixture and this creates a hygroscopic nature to the fuel.

They recommend that on the first fill you should have a damn-as-near empty tank to help reduce the moisture draw out the existing fuel, and that you should keep the tank as full as possible.

[MSTRS]

Who needs that hassle? Unless you have a plastic tank. And a water-separating filter somewhere in the fuel line.

[XP@]

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

[nosebleed]

thats pretty much the main reason I've avoided using it myself.
I'm a real fan boi of Gull, but thats (as you point out) too much hassle for a fuel thats not readily available

[Cheshire Cat]

You are new...
This site has a 10 character minimum per post. "+1" means they agree, but it's not enough characters...


OH! ok:doh: lol

[kevfromcoro]

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]

OH! ok:doh: 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. :laugh:

[Cheshire Cat]

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]

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]

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

[Cheshire Cat]

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]

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]

Lately I've noticed my bike is backfiring alot:confused: 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....:confused:

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]

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......:blink:


Thats Goblins hornet.

[rosie631]

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]

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.


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]

Took the tank off today and straightened that pipe.Looks like some one put it back togther wrong :bash: and we found water and rust in the tank :angry:
will be cleaning that out soon.

[Max Preload]

...and we found water and rust in the tank :angry:
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]

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.

:eek:

[Cheshire Cat]

So where on the exhaust to i check for leaks? :confused:

[steve_t]

So where on the exhaust to i check for leaks? :confused:

If you can't see any holes, check the joins are all tight :msn-wink:

[Max Preload]

So where on the exhaust to i check for leaks? :confused:

Start the engine, have someone partially block the exhaust using a rag over the end and then work your way along from the engine down the length of the exhaust while listening for the telltale hissing of exhaust gasses escaping where they shouldn't be.

[samgab]

So where on the exhaust to i check for leaks? :confused:

If the pipe is cool you can put your hand over the exhaust pipe to seal it. You'll soon know if there is a leak that way.

[MSTRS]

So where on the exhaust to i check for leaks? :confused:

Start the engine and have someone put something (the sole of their shoe?) over the tailpipe. This will have the effect of making any leak more obvious. Look by cupping your hand/s around the pipe, without actually touching it, and then run along the entire length of the pipe. If there is a leak you will feel air puffing against your hand. Be aware that there is often a hole underneath towards the front of the muffler. This is to allow any water, either rain, washing or condensation, that gets into the muffler to drain.

[Cheshire Cat]

Start the engine and have someone put something (the sole of their shoe?) over the tailpipe. This will have the effect of making any leak more obvious. Look by cupping your hand/s around the pipe, without actually touching it, and then run along the entire length of the pipe. If there is a leak you will feel air puffing against your hand. Be aware that there is often a hole underneath towards the front of the muffler. This is to allow any water, either rain, washing or condensation, that gets into the muffler to drain.

ok. I'll do that now :)

[NDORFN]

I'll have a look when we go for a ride. I'll bet you anything it's a high-flow exhaust that hasn't been jetted to suit. Everyone does that. Dummies! (not you, the person you bought the bike off).