Reply
 
LinkBack Thread Tools Display Modes
Old 05-28-2008, 02:10 PM   #1
Knee Dragger
A4wheelin's Avatar
OP
 
Joined: Aug 2007
From: Portland, OR

I Ride: 2001 Suzuki Bandit 1200S
Why does my bike backfire???
Recently my bike has been back firing when I let off the gas. Sometimes one pop, other times a series of pops. What causes this and how do I fix it? Is it really a big issue? Thanks!

__________________
Follow PNW Riders on Facebook and Twitter
 

Old 05-28-2008, 02:11 PM   #2
Streetfighter
gixer_racer's Avatar
 
Joined: Jun 2007
From: Covington, WA

I Ride: RC51, R6 (track), Ninja250
Probably a small exhaust leak? Check the joints/gaskets in the exhaust system.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 02:27 PM   #3
Pit Crew
FuNCHun's Avatar
 
Joined: Feb 2007
From: Seattle, WA

I Ride: 2001 VFR 800fi
I'm no expert but I think popping once in a while is normal. I got an '06 gsxr 600 and it pops when i let off the gas at higher RPMs. Dont know much about carbureted bikes though.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 02:31 PM   #4
Licensed
 
Joined: Mar 2007
From: Bonney Lake/Sumner

I Ride: 07 gsxr 1000
My 07 GSXR 1000 does the same after I put an exhaust and power commander on it. I've been told that its just fuel that hasnt been burned and gets into the exhaust and when it gets the right air and heat it egnites. Not sure this is correct or not. I also dont think its bad but the only reason I say that is the one time I went to the track I think most of those guys had the same thing.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 02:33 PM   #5
Forum Cripple
tophyr's Avatar
 
Joined: Dec 2005
From: Seattle, WA
Blog Entries: 13

I Ride: on the Isle of Man
Too rich.

Have you recent re-mapped/re-jetted/modified your bike in any way?

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 02:35 PM   #6
Forum Cripple
tophyr's Avatar
 
Joined: Dec 2005
From: Seattle, WA
Blog Entries: 13

I Ride: on the Isle of Man
“ Quote:
Originally Posted by d_fuhrmann131313 View Post
My 07 GSXR 1000 does the same after I put an exhaust and power commander on it. I've been told that its just fuel that hasnt been burned and gets into the exhaust and when it gets the right air and heat it egnites. Not sure this is correct or not. I also dont think its bad but the only reason I say that is the one time I went to the track I think most of those guys had the same thing.
A lot of track bikes "burble" when they're off the throttle.. this is different than backfiring. Burbling is a "problem", but track guys don't care about it because it indicates poor off-throttle mapping, and they only usually care about WOT. Backfiring, on the other hand, is a problem.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 02:38 PM   #7
Novice Racer
wordsareforplay's Avatar
 
Joined: Aug 2006
From: Around
“ Quote:
Originally Posted by tophyr View Post
A lot of track bikes "burble" when they're off the throttle.. this is different than backfiring. Burbling is a "problem", but track guys don't care about it because it indicates poor off-throttle mapping, and they only usually care about WOT. Backfiring, on the other hand, is a problem.
So who can he contact to have his stuff dyno mapped out correctly?

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 02:40 PM   #8
Forum Cripple
tophyr's Avatar
 
Joined: Dec 2005
From: Seattle, WA
Blog Entries: 13

I Ride: on the Isle of Man
His F3 is a carb'ed bike, so it might not be worth some intense dyno time. But, given that he's in Portland, EDR is where I'd go.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 02:44 PM   #9
Moto2 Contender
JohnnyM's Avatar
 
Joined: Jul 2006
From: Pullman, WA

I Ride: '73 CB350F, '86 VFR750F, '00 Aprilia RS250, '04 Aprilia RSV1000 R Factory, '04 Aprilia RSV1000 R Factory, '07 Vstar 1100 Classic
“ Quote:
Originally Posted by tophyr View Post
Too rich.

Have you recent re-mapped/re-jetted/modified your bike in any way?

It could also be caused by dirty plugs. A weak or occasionally missing spark will keep it from burning all the fuel.

A bad coil could be causing weak or missing spark as well, but usually it is the simplest answer as opposed to some part of the ignition system farther down the line.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 03:17 PM   #10
Streetfighter
Mithras's Avatar
 
Joined: Apr 2008
From: Silverdale, WA 98383
Blog Entries: 1

I Ride: Yamaha YX600
A couple possible factors:

A change in back pressure of the exhaust system. (like changing your exhaust or getting rid of a cat. converter if your bike came with one. Higher flow systems generally mess with the fuel mapping of your system causing more fuel to be used and since it doesn't burn completely it gets superheated and pushed out the back) ...which brings me to ->

Engine not completely burning fuel and upon exiting the exhaust tube mixes with enough oxygen in the air to combust. (backfire)

Leak in the exhaust pipe somewhere enabling oxygen to enter the system creating secondary combustions (backfires)

Basically the problem is the engine not completely burning all of the fuel that's pumped into it. "running too rich" If your exhaust smells of gas and you have a lot of carbon deposits this might be the case.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 03:20 PM   #11
JTR
Novice Racer
JTR's Avatar
 
Joined: Feb 2006
From: Ames Lake- Lauralhurst hood

I Ride: Yamdalarisosaki's w/ a nos!
been thu this myself and it was a lean condition...

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 04:44 PM   #12
Knee Dragger
A4wheelin's Avatar
OP
 
Joined: Aug 2007
From: Portland, OR

I Ride: 2001 Suzuki Bandit 1200S
Thanks for all the answers guys! I remember it doing this every once in a long while. I couldn't figure out what the noise was though. Now it pretty much happens anytime I let off the throttle. I haven't done any modding or tuning at all. I did run the bike without the exhaust pipe for a day last week. But besides that nothing else has been changed. It doens't bother me any I just didn't know if it would cause any damage or anything.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 05:18 PM   #13
Shredder
SpeedGeek's Avatar
 
Joined: Jan 2007
From: Lake Osghetto, OR

I Ride: the Milk Truck!
It is likely running LEAN. Take it to EDR and have him check the air/fuel ratio on the dyno. Backfiring is only a SYMPTOM. A lean running bike can also run HOT when the temp warms up, and you can burn valves etc... Backfiring is NOT normal and you really should get it checked out.

EDR: 503-222-race

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 10:07 PM   #14
Superbiker
 
Joined: Dec 2005
From: Marysville

I Ride: A lifted JK 0|||||||0
here are the possible causes:

1) normal operation or air injection system (yes it is suppose to do that)
2) free flowing exhaust system (they do that too)
3) fuel mixture too lean at low speed
4) fuel mixture too rich at low speed
5) air entering exhaust system
6) incorrect ignition timing
7) water in fuel (will also misfire during acceleration)

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 10:09 PM   #15
Moderator
Grantizzle's Avatar
 
Joined: Feb 2008
From: Mill Creek, Wa

I Ride: slower than you with a bigger grin!
“ Quote:
Originally Posted by A4wheelin View Post
Recently my bike has been back firing when I let off the gas. Sometimes one pop, other times a series of pops. What causes this and how do I fix it?
cause: touching yourself too much

fix: touch yourself less or touch others more.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 11:22 PM   #16
Shredder
FastCat's Avatar
 
Joined: Dec 2005
From: nowhere, wa
Geez, I have no idea why, but this is one of my pet-peeves.

What you are describing is not a "backfire".

THIS:



....is a backfire.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 11:28 PM   #17
emw2k9 beer pong champions
Kolat's Avatar
 
Joined: May 2005
From: Eastern central washington

I Ride: Wheelies
put the bike in neutral.....

pin the throttle, when the rpm's get about halfway up click the kill switch off then on :-)

makes one helluva backfire on carb'd bikes, though I've heard of it blowing up motors too /shrug.

T

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 11:30 PM   #18
Shredder
FastCat's Avatar
 
Joined: Dec 2005
From: nowhere, wa
“ Quote:
Originally Posted by Kolat View Post
put the bike in neutral.....

pin the throttle, when the rpm's get about halfway up click the kill switch off then on :-)

makes one helluva backfire on carb'd bikes, though I've heard of it blowing up motors too /shrug.

T
Nope, that is not a "backfire" either.

...although it's very LOUD.

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-28-2008, 11:50 PM   #19
Streetfighter
Mithras's Avatar
 
Joined: Apr 2008
From: Silverdale, WA 98383
Blog Entries: 1

I Ride: Yamaha YX600
“ Quote:
Originally Posted by Kolat View Post
put the bike in neutral.....

pin the throttle, when the rpm's get about halfway up click the kill switch off then on :-)

makes one helluva backfire on carb'd bikes, though I've heard of it blowing up motors too /shrug.

T
You Sir! ...are a very bad influence...

__________________
Follow PNW Riders on Facebook and Twitter
 
Old 05-29-2008, 02:43 AM   #20
Shredder
FastCat's Avatar
 
Joined: Dec 2005
From: nowhere, wa
(poppity-pop-BANG-pop-pop,poppity-pop)

...nope... that's not a backfire.



...now, THAT's a backfire.

__________________
Follow PNW Riders on Facebook and Twitter
 
Reply

  PNW Riders > PNW Riders > Mechanical & Technical


Thread Tools
Display Modes



/pnwriders @pnwriders PNW Riders RSS Feed