Backfire

[Capo79]

Hi guys!

Went for a run today, and for the first time after I installed the devil's, I noticed a few bangs when I went off the throttle. I thought of it as kind of cool (a bit macho:rockon, but does your bikes do that? I know why I get the backfire, though. Unburned fuel, etc. But I think it's pretty weird that I haven't heard it with the original exhaust before..

 

[dako81]

Hi guys!

Went for a run today, and for the first time after I installed the devil's, I noticed a few bangs when I went off the throttle. I thought of it as kind of cool (a bit macho:rockon, but does your bikes do that? I know why I get the backfire, though. Unburned fuel, etc. But I think it's pretty weird that I haven't heard it with the original exhaust before..

From what I've learned on here by many experienced fellows, backfire or popping is the result of a lean condition.

Well, actually, an actual real backfire is almost always the result of a timing issue, but the popping on decel is a result of a lean condition.

 

[Capo79]

You have to excuse my french, but what do you mean by "lean conditions"? Thanks for the reply, though:thumbup:

 

[dako81]

You have to excuse my french, but what do you mean by "lean conditions"? Thanks for the reply, though:thumbup:

The air to fuel ratio, A/F, is too lean. Not enough fuel. The fuel trim needs to be "fattened up" or "richened up".

No problem!

 

[Capo79]

The air to fuel ratio, A/F, is too lean. Not enough fuel. The fuel trim needs to be "fattened up" or "richened up".

No problem!

Ah... of course. As the opposite of "too fat". Should have known that:ban:

Thanks, though:thumbup:

 

[adavi491]

Mine backfires every once in a while on deceleration as well. I might have the dealer look at it when i get it inspected in May. When i got it inspected last July the mechanic told me it was a nice bike and that it very definitely had been tuned. He said the sound was awesome and the performance was good... he didn't say anything about the backfiring. I just assumed it was part of having aftermarket exhaust (leo's) and the tuned engine. Oh and i think it only does it when the engine is still cold in the morning when i go to work.

 

[Capo79]

...Oh and i think it only does it when the engine is still cold in the morning when i go to work.

That's a very good point! Sure, the popping is more distinct when the engine is still cold. That made me a bit more calm about the whole thing. First that came to mind, was bad timing as dako mentioned in his first post:thumbup:

 

[McLovin]

fz6 backfires no matter what, you can hardly hear it with the stock pipes, when you put on aftermarkets then you really hear it, i was worried about running lean n stuff too when i put on two bros, then another forum member i ride with cleared this issue...your bike is fine enjoy your pipes

 

[Gilo-FZ6]

That's a very good point! Sure, the popping is more distinct when the engine is still cold. That made me a bit more calm about the whole thing. First that came to mind, was bad timing as dako mentioned in his first post:thumbup:

but here lies the paradox..when the engine is cold its running rich not lean

popping on over-run with open pipes is perfectly natural..all my tuned cars have done it and all 3 of my bikes have done it..even with re-jets

 

[AJ_rider]

Backfires are normal with an aftermarket exhaust, never had them (or noticed them) with the stock exhaust but when I put the TBR cans on I was getting them all the time.

 

[CdnMedic]

It's normal.
Unless when you let of its a constant succession of popping, then I would be concerned. But if its a couple snaps when you get off the throttle, its fine... Enjoy the sound!
With my drilled baffles I hear it pop a little bit, i expect to hear it alot more when my exhaust gets here.
My YZ250F pops all the time and it's not lean. Some guys have bikes that are lean and you can tell, they pop way too much, and sound "flat" when they are on the gas.
Every vehicle I've owned has had an aftermarket exhaust, and popping is normal!

 

[Wildcard]

popping on over-run with open pipes is perfectly natural..all my tuned cars have done it and all 3 of my bikes have done it..even with re-jets

Exactly. Now you know if your timing is off or you are running extremely rich when it actually backfires and you see flames out the exhaust. My 240 did that and was quite awesome hahaha

 

[SovietRobot]

You're hearing unburnt fuel combine with superheated air introduced into the exhaust stroke by the AIS system.

Fuel + Air + Heat = Boom