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Running lean with Cobra Fi2000. What gives?

14193 Views 58 Replies 24 Participants Last post by  rarebit
Well, guys, I put my shiny new exhaust on earlier this week and now there's trouble. A little background:

I drilled my stock exhaust a bit at first, no issues there. Then I got the Fi2000 CVT, installed that. No issues there. The old butt-dyno even told me it did some good with the low-rpm lugging through town.

Next I got the Baron's BAK put on there. That was a bit disappointing. The holes in the cover plate weren't tapped properly - I had to tap them out myself. For what that thing costs, you'd figure... well, anyway, I thought it made throttle response a bit snappier through the whole range.

Now, for the bit where it turns bad. I finally got my V&H Twin Slash Staggered pipes. In black. I put them on without any issues. They look fantastic. They sound great. But the bike's performance has gone a bit strange. It misses at odd times. Weird flat spots. If I'm accelerating hard through the gears, it's got some serious oomph and no issues. If I'm just cruising at 60 in 5th, it misfires at random.

It got really bad this morning when I was putting around in 2nd gear, 30-40mph. It was stuttering so bad I thought it was going to keel over. Quite a jerky ride. So I got home this morning and checked the spark plugs, and they're very, very white.

Obviously, I've got a problem. The question is, what else should I check before I start making angry calls to Cobra?
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Here is a couple of charts to compare to. The grey deposits on the white porcline are usly a sign of a lean condition, overall it looks pretty good , 2 plugs don't cost that much now that your mods are installed I would put in new plugs drive it for a while and then check again.

Mentat said:
Well, I'm puttering around double and tripple checking that I dont have any intake or exhaust leaks before I get Cobra tech support involved - I'm sure there's nothing wrong with the intake, and I haven't figured out a conclusive test for the exhuast yet... I started the bike up in the dark, no flames... there's no soot buildup anywhere... don't hear anything odd... blew some smoke around the exhaust ports and didnt see anything..

Anyhow, happened to get a good look at the pipes under the heat sheilds during all this, and holy crapola. The front header is bright blue for at least 10", and the back is blue for 2" or 3". I thought I noticed the fan running more than usual right after I put the pipes on, but I didn't think it was getting that hot...

I'm not even sure I should be riding this thing any more until I figure something out.
call Phil @ Cobra and talk with him he will lead you in the right dirrection.
I just called Phil at cobra and explaned the problem to him that some of it are having ,well wait and see what happens I guess ,he was going to talk to his boss.
Bozzly said:
I think it is with the Vance & Hines as I have cobra intake, swepts and tuner. The bike runs like a dream.
Does it ever pop on hard decell ?
Bozzly said:
clar2001 said:
Bozzly said:
I think it is with the Vance & Hines as I have cobra intake, swepts and tuner. The bike runs like a dream.
Does it ever pop on hard decell ?
ok, you caught me Clar, If I hammer it hard then quickly decel, I get more of a growl then a backfire or pop. I rarely really ride that way. I try to be pretty steady on the throttle, Now it does pop once in a while but hardly ever, maybe I just don't ride it hard enough to get it.
Most of the time mine just growls to if its a hard enought decell at any speed it will pop once and a while.
The first time I talked to Phil at cobra they e-mailed a page related to exaust leaks ,I have taken my exaust off twice and with a streight edge planed my header flanges & installed new gaskets made no difference, unless I did not correct the issue, but since there are several of us having this issue, I can't beleive we all have exaust leaks.
So I waiting to see what cobra says , I have little faith in any resove here , I wondering if there is a softer gasget I could install to try to correct/resolve this issue make sure there is no leak, the bike runs great it just that pop that bothers me.
midlifecrisis said:
Not directly. I'm talking with Mike who said he, Phil, and some of the other engineers are working to solve this issue. They acknowledged I was not the only one having this issue.
I talked to phil about this problem that myself and others on here are having a couple days ago still waiting to here back < I dont think they have a sloution yeat.
I to might try hooking the 02sensor back into the ECU and see what happens.
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