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Backfire

D94

D94

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Jan 31, 2015
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I just installed a decatted headpipe om my 15 SGS last night along with the FL-VIED-10 last night. I'm also using RCX slip-ons. After I installed the pipe and mufflers I fired it up to check it and it seemed fine. Then I installed the vied's. I set them to the recommended 50% setting and noticed a backfire when I gave the throttle a quick blip. Seems to idle ok. I tried a couple of different settings but it still seems to be happen every so often. I haven't had a chance to drive it yet because of the weather. Has anyone experienced this? Any advice? Thx.
 
Decel Pop is normal. I'm currently running stock header with cat and CFR slip ons and stock tune and air cleaner and get decel pop


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BB I respectfully disagree I don't think decel pop is normal and your bike shouldn't do it. If you have a good tune on the bike it wount pop or backfire. D94 if you can't get rid of the backfire, I would have it tuned.... Just my two cents
 
Backfire

I had decel pop from day one its just louder now due to the slipos. I live on a main artery into the city and hear a lot of decel pop all summer. I am a green horn HD owner. From hearing traffic ride buy and having the issue since day one figured it was just a HD thing. I stand corrected.


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I get a bit of decel pop as well. Stock header with cat and gutted stock mufflers. Eventually I'll get a tune, but as far as I can tell it's not hurting anything in the meantime.

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" noticed a backfire when I gave the throttle a quick blip"

I don't think he is talking about a decel pop. Sounds like a fuel issue, could be a touch on the rich side.
 
Crumb, so you're thinkin' the vied's aren't enough? I still have stock a/c. I thought it was maybe something in the setting, but maybe I'll have to spring for the FP3.
 
Gunner said:
" noticed a backfire when I gave the throttle a quick blip"

I don't think he is talking about a decel pop. Sounds like a fuel issue, could be a touch on the rich side.
Click to expand...

It most likely is a fuel issue, but I doubt he is rich.... the VIED only gives a max of 6% enrichment of AFR over stock when it's at 100%... if he is at 50% on the VIED, it's only a 3% increase over stock AFR. That being said, the VIED is a piggy-back unit and richens the AFR across the board with no variation in regard to timing advancement and retardation driven by the ECM. With a de-cat.... I am thinking he is still a bit lean.

When I had my VIED with a decat and Rhineharts.... My perfect setting with no pop was 75%..... give that a shot.
 
D94 said:
Crumb, so you're thinkin' the vied's aren't enough? I still have stock a/c. I thought it was maybe something in the setting, but maybe I'll have to spring for the FP3.
Click to expand...

The 1st change I had made to my exhaust was to mod the mufflers basically gutting them but adding a homemade baffle. I got the popping noise on acceleration. Decel was fine.

But speaking of FP3, now that I changed my exhaust to V&H pro-pipe, FP3 tuner, with the stock air cleaner - almost all of the accel pop is gone (if not all). It use to happen every time I would take off. BUT...I have only ridden 2 days this year with last year's gas still in the bike and have not done the auto-tune yet. I'm waiting for fresh gas in the tank and for it to get a bit warmer out to do the auto tune. Expecting that will take care of the rest of the needed tuning (though it still runs great, sounds great, has a lot better throttle response too). So another impress with FP3 customer here.
 
The FP3 is a great tuner... I have one and couldn't be happier. I have had many forum members hit me up with questions/help with their FP3 and auto-tune sessions...and so far... they are all 'happy campers'.

You can't go wrong with the FP3... HOWEVER... for those with built engine ( cams, headwork.etc.. ) they are not able to tune yet... they will get there.
 
Ok. I'll try bumping it up to 75% and see. I was afraid to go to high because the backfire meant I was getting to much fuel.
 
If it wasn't popping before the VIED how could it be a lean condition. All the VIED will do is add more fuel.
Unless I'm missing something here. He is still running a stock ac. So he has done nothing to create a lean condition in a closed loop set up with the sensors feeding data back to the ECM.

Just thinking out load. :)
 
Gunner, you're saying I don't need anything until I change the a/c? Maybe I'll just turn them off until I change? It's ok to run it like normal for now?
 
He installed the pipe and slip-ons... he said he fired it up and was fine.... I am thinkin out loud as well... lol.

Maybe he didn't let it warm up enough to get the pop at engine temp? Closed loop system enriches during starts and warm-up period. After it warmed up and it 'settled down'... it could have went to a lean condition due to decrease in back pressure.

... follow me Gunner?

ADD-ON:

Note this... IF he is firing it up and not letting it warm up to temp and blip-pops are occurring.. you could be right on the rich factor.... hmmm.....

D94....are you allowing the bike to come to temp BEFORE you are 'testing' for accel pop?
 
I thought temp was ok. I had it running on and off numerous times while checking. Maybe not the first time when I tested just the pipe, I just fired it up to check for anything wierd like idle, warning lights, etc. Good call though. Do I have to drive this for the ecm to adjust a little?
 
D94 said:
I thought temp was ok. I had it running on and off numerous times while checking. Maybe not the first time when I tested just the pipe, I just fired it up to check for anything wierd like idle, warning lights, etc. Good call though. Do I have to drive this for the ecm to adjust a little?
Click to expand...

No.... just idling is fine until the RPMs settle down to around ~1000 or so..... you will know...

Since the VIED is piggy-backed between the O2's and the ECM... it actually tricks the ECM into thinking they are still running at the stock stepoints when in fact you are richening it up with the VIED
 
Another thought I came across while researching last night, was it could be exhaust leak? According to what I've read and some I have talked to, they didn't think I would need to replace the exhaust gaskets. My bike only has about 50+miles on it, should be ok. Is it possible I could have a leak there? How do I check for sure? I didn't see or here anything coming from the flanges, is there simple way?
 
D94 said:
Another thought I came across while researching last night, was it could be exhaust leak? According to what I've read and some I have talked to, they didn't think I would need to replace the exhaust gaskets. My bike only has about 50+miles on it, should be ok. Is it possible I could have a leak there? How do I check for sure? I didn't see or here anything coming from the flanges, is there simple way?
Click to expand...

It is possible...

I have had my pipes off and on 3 different times and never changed gaskets... no leaks on my end. over 14k on my sled now.

The best way to seat the pipes is by hand tightening ( 1/2" socket on a 3-6" extension ) and ensure the collector flanges are even against the surface of the collector rings prior to tightening with a wrench and don't wrench down on one side completely... alternate about 1/4 turn per side until you reach the torque spec.

Always check your flange nuts after a few hundred miles on an install.. they will be loose.
 
If it is still doing it, try and see where it it backfiring. As a general rule if it is out of the intake it is lean. Out the pipes it is fat.
 
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