Backfire and Engine Light

[kalali]

Lefox,

"....if you don't want to risk anything, go back to the stock...."

Well, I went ahead and put the stock muffler back on this weekend. I rode the bike yesterday and this morning to work and the decel popping and backfire all disappeared. Or may be I just can't hear them any longer!! The acceleration also feels more linear even with a semi cold motor. So, all in all, it looks like a good move except the bike does feel to have lost a little oomph, but not much. And needles to say, my wife and neighbors all seem to approve the switch! I will keep it this way until I find someone in the area who could help me with the tuning. My main issue now is a leak in the gasket between the starter and the primay. Looks like a lot of work to remove a lot of pieces to get to the gasket. Omce again, thanks for all your input.

 

[LeFox]

no problem, kalali.

just on a sidenote, a little decel popping is normal with an open exhaust, but the backfire shouldn't be happening.

 

[kalali]

Well, after riding with the stock exhaust for a week or so I have realized I really miss the V&H sound and the extra oomph.
So I opened the backplate of the V&H to see what is inside..Well, no baffle and no packing material, just a hollow can!
The previous owner must have thought removing the baffle/packing would help with performance but on the contrary (according to the V&H folks) it hurts the performance just makes the exhaust louder.
I went ahead and ordered the baffle and the packng from V&H and I am hoping that with the baffle and the packing the mixture will not be quite as lean and I should be able to "teach" the ECM to work and hopefully the occasional backfires will not happen again...
LeFox, what do you think?

 

[teh Nub]

Back to FIDO's air box backfire, I have had a few airbox back fires occur on my XB12Ss when the bike is cold, usually when slowing down and and bliping the throttle. I first noticed this after resetting my TPS for the first time and leaving idle adjustment at 4.6 deg and 5.1% as the ecmspy states in the tuning manual (idle is right at 800 rpm give or take). The idle was probably a few hundred rpm above that when I took ownership of the bike. I have since done the white wire mod and crankcase/cylinder vent to airbox delete mod, fallowed by another TPS reset and AFV reset. Previous AFV was 105. Bike is stock with the exception of the previous mentioned items... Enough rambling for now....

 

[LeFox]

LeFox, what do you think?

well, personally i would not add the baffle, but...it's your choice.

the packing is good though, that will deffinatly help with the backfires.
but about running to lean...except for remap, nothing will change the mixture like it should do.

but it will run...

 

[kalali]

LeFox, as always thanks for the quick response.
My understanding was that the packing actually "wraps" around (or slides over) the baffle and without the baffle (which is essentially just a long tube) I wouldn't be able to use the packing. I will see when I recieve them in a couple of days...

 

[LeFox]

oh ok...i thought you ment a baffle to have lesser noise (smaller insert), not the interior one

yea, you need to bigger punctured pipe for the interior.

 

[BuellS1Culver]

I had the same problem with my bike when i first got it. (1996 S1). A backfire is when one of two things happens, 1: you have to much air in the air-fuel mix
2: you have an exhaust leak, ex. air is escaping before leaving the muffler.
The engine light on my bike did not go off, but being a first year model, it doesn't have a computer in it. Always remember to cheek the basics and !!ALWAYS!! but !!GOOD!! fuel in your bike!

 

[kalali]

Quick update. I went ahead and ordered the baffle and the packing and put it all together abd back on the bike. After a couple of days of riding including the steady 3000+ RPM for 15-20 minutes to get the closed loop learning out of the way, it looks like the backfire issue has been resolved. I still do get a little decel pop but it is in the normal range. It looks like taking the baffle/packing out pushed the mixture too much into the lean zone for the ECM to compensate. I will see how it goes but so far I am a happy camper.

 

[LeFox]

[up]

good for you!

now you can enjoy the buell symphony while riding