I posted this on Cbrworld as well but I'm trying to appeal to the broadest audience[8D]so any help would be appreciated.

Ok I have searched around bit and posted before, but I am still having problems with sputtering at low rpms (under 4000)
My bike: 02 f4i, APE cam chain tensioner, two brothers V.A.L.E slip on, power commander with two brothers map from powercommander.com, anything else is just cosmetic.
Situation: Bike starts and idles fine. No noticeable low rpm power issues (i.e. acceleration is fine even from stopped position). I get a sputtering/popping sound at lower rpms but especially when I let off the throttle. I sometimes smell gas (unless I am going crazy). I do not see smoke or flames from the exhaust. Battery connections are fine (just connected my PC so I checked the connections at that time)
I am confused for a few reasonsI thought sputtering indicates running lean and gas smell indicates running rich? Also the power commander smoothed out the problem a bit. The problem used to happen in the midrange rpm as well (around 5-6k) and the PC got rid of that.
I thought maybe fuel pressure regulator, but don't you get start and idle problems with that issue?
I'm new to self dianosis so bear with me. If you have any ideas of what I should check next or need other info let me know.
One other thing I have the two brothers p1r silencer installed, but I doubt that would cause sputtering. I could be wrong.
Thanks
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my first idea is FPR.. however your symptoms are a bit different then i'm accustomed to seeing

however, if your idle valve is set real high to give it more gas at start you wont notice the starting problems others have. if you are smelling gas(out of the exhaust i assume?) it means its running rich. one of the more common fixes for this is the fpr. it'd be nice to know a little history behind this bike. has it ever sat for a couple months or longer? what kinda mpg are you getting?

be sure to check all your vacuum lines, even the FPR runs off vacuum, so if a line is kinked or has a slice in it, you'll def notice the effects.

good luck in healin that sick f4i

 

+1 on the FPR, very common problem with the f4i's....Pull the tank and pull the airbox....Take the vacumm hose that runs from the FPR into the #2 and #3 cylinders of the throttle bodies. IF you have gas in that vaccum, chances are its going bad. When it goes bad it allows gas to flow into the #2 and #3 cylinder, causing the bike to flood...It will rum perfect at idle (when warming up), and it'll run perfect as long as your on the throttle..........Common symptoms is, it will not hold an idle once it warms up (it just dies). Smells really rich as though gas is just pouring out of the exhaust. Also, sometimes it will blow white smoke from the exhaust..........I'd check it just to eliminate the potential problem. You may find that its actually the cause of the problem....Well worth the 15mins it would take to check it....=-)

 

Ok looks like I'll try checking the FPR. May be a few days before I have a chance to do it.

A little more info about the bike. I've had it for two years. Has 16500 miles. Just started with this problem last month and it hasn't sat for longer than a few days since I took it out of winter storage in march.

thanks guys.