Scorpion Exhaust & PCIII: Pops on de-acceleration?

[Thatguy331]

Hey all,

I bought a 2005 FZ6 with a Scorpion Exhaust and a Power Commander III. I just checked the PCIII and it is set with the data for a stock bike with Scorpion exhaust.

So when I'm de-accelerating, the exhaust sounds poppy... is that backfiring and is that bad, or just something to expect with the use of an after market exhaust like that?

Its new to me so I just want to make sure its *normal* and not *zomg its gonna blow*

[wrightme43]

Mine does it with out a pcIII. I may be wrong but I think its because the back pressure is a lot lower, and its pulling unburnt fuel air mix out and burning it in the exhaust.

[bmccrary]

It was always my understanding that poping on decel is a sign of being lean. I would try richening it up some and see if it gets better.

-bryan

[Thatguy331]

Originally Posted by bmccrary

It was always my understanding that poping on decel is a sign of being lean. I would try richening it up some and see if it gets better.

-bryan

I'm not sure I really feel comfortable yet messing with the settings in the PCIII, I'm hoping maybe someone around here has gone through the same thing I am and have already altered their map accordingly and wouldn't mind sharing

If not, I guess I'll have to read up on it and try and do it myself. I'm surprised the PCIII map from their website for stock + scorpion would be that far off from what it should be???

[OneTrack]

I'd say it's part of the deal. My 06 with Scorpions, PCIII and K&N filter will pop on decel. I kind of like it now.
Check your exhaust system for leaks, btw..that will also cause backfiring in the exhaust.
The PCIII MAP for the above mods shows that the mixture is heavily enrichened at anything under 1500 rpm, which will cause the backfiring.
Look on the bright side...there's no baffles to blow out.
I suspect my backfiring is directly associated with my fuel consumption going from 45mpg to 35mpg.

Edited by me. Never attempt to talk about anything more technical than blue vs red when you're jet-lagged and after a few beers in Orlando.

[Hellgate]

Originally Posted by bmccrary

It was always my understanding that poping on decel is a sign of being lean. I would try richening it up some and see if it gets better.

-bryan

It's the opposite, it's probably fat. The fuel is burning in the exhaust path, hence the pop. Typically this happens in a decel because the of the negative pressure in trailing throttle, the exhaust is over scavaging the engine. No biggy, sounds cool.

If I'm not mistaken the PCIII gives an air to fuel ratio. 14:1 is the goal, usually.

[OneTrack]

Either too lean or too rich will cause a "pop" in the exhaust. The difference is a lean "pop" will give you a bit of a burble with the occasional "snap, crackle and pop". Rich will do the same, except that it can and will give you a Big Bang that will blow off the end of the muffler from unburnt fuel gathering inside the muffler.

[wrightme43]

I can just go on my experince in the past. My bike smells rich, not overly rich, not unburnt rich, just rich. For all thats worth, though, its just my bike and my nose. No o2 sensor data to back it up.

[Nooj]

The Missus' bike does it with the Remus Revolutions she has on it. Sounds good, enjoy it, it's not damaging anything.

[reiobard]

My old bike did it with an aftermarket exhaust and the wifes bike also does it. Never really had any problems, i kind of like the popping.