My 04 S4R (996 motor) has Arrow cans, no cat, and some kind of ECU treatment (previous owner did it all, I don't know the specifics).  It backfires pretty much every time I decelerate.  At night you can see 10-inch flames shooting out the tip* (now I know why the one exhaust company is call "BlueFlame"!). I think it's all great, the sound is fun and adds to the rawness of the bike, which I enjoy.

...but I was wondering if I should be concerned about anything going wrong, or perhaps that the backfires are evidence of something going wrong?

TTYS.  I can only get on the internet about twice a week so be patient if I'm slow with my responses.  Thanks all!

* - I can only see it coming out the top pipe, but I haven't exactly spent a long time riding around at night with the throttle shut off while I look behind me...

if flames are shooting out, there is unburnt fuel, aka a rich condition going on. heat and pressure in your exahust causes it to ignite again. How do your sparkplugs look?

My bike's definitely rich, you can smell it.  But I'm not real handy working on bikes.  What's the best way to get the best air/fuel ratio if the bike's not stock?  Do I have to dyno-tune it?

And again...aside from spark-plug fouling, backfiring is...fun/whatever/bad?

backfires and 10 inch flames shooting out your exhaust?  good..bad?   








its freakin awesome!!!!

on topic, like he man said, its because your running rich.  i would try to pick the previous owners brain about the specifics of the modifications that were performed.  probably have him write it down, not to insult you but specifics sometimes get lost in translation.

lift your tank. do you see a device that says POWERCOMMANDER ? or a box like object anywhere? if not. get a used ond and program that sucka, you might be able to get away with just going to the dealership and getting them to tweak the ecu a bit though.

Your first step should be to contact the origional owner.  Before doing any modifications make sure all base settings are correct (TPS, idle CO, cylinder synch, etc).

Or better: post a vid on the forum, so we can all enjoy the flames 

How come he gets flames & I don't???


I want flames too!!!

Quote from: Lukey on May 24, 2008, 07:57:13 PM
At night you can see 10-inch flames shooting out the tip

Did you have to pay extra for that?  Way cool 

as cool as that is, it shouldn't be doing that, definitely should have your mixture fixed up

Quote from: knightrider on May 24, 2008, 10:08:28 PM
backfires and 10 inch flames shooting out your exhaust?  good..bad?   








its freakin awesome!!!!

+1 - Gonna draw some attention from officer Bob though...

on topic, like he man said, its because your running rich.  i would try to pick the previous owners brain about the specifics of the modifications that were performed.  probably have him write it down, not to insult you but specifics sometimes get lost in translation.

Try adding 2-3 degrees of advance.

My 996 SPS does the same thing. Full 54mm Arrow system+some sort of chip- so says the owner. The bike runs rich 'cuz I can smell her too. Gonna have to do some diagnostic work to se if the cO and so forth are set correctly. FlightCycles gave her a once over and said thats to be expected.


BTW the Flames R-O-C-K!!!

The only consequence of running rich (other than fuel economy.... bah) is that you'll eat spark plugs and overall, things will get pretty mucky over time.  You will notice your bike running worse and worse the more the gunk builds up.  It sounds like you might want to go for a dyno tune.

sweeeeeeeeeeeeeet!  seriously.