This might be long. Apologies in advance!
First, the background. I had a bit of a highside at the end of last season. Long story short, cold ground + cold tire = little traction. Part of the damage required a new right-side clipon. Since the throttle cables were already disconnected at one end and I was going to change plugs anyway, I decided to change the throttle cables as well as the clutch cable. Everything went smoothly and the bike showed no signs of trouble after buttoning everything up and starting it. Due to the glorious misery that is New England weather, there have been few riding days since the beginning of "spring". The bike sat in the garage for a two to three week period. During that time, I purchased an HTEV eliminator from Hass Motorsports (a side note: they are great folks to work with. The part is well constructed and was a cinch to get installed. Nice work by those guys) and installed it. It also came with a new PC3 map, which I dropped in. During my season maiden voyage, I noticed things I hadn't before. For starters, it seemed that the fuel pump was running a little louder than normal. While I noted it, I didn't pay all that much attention because I was being overly critical of noises since I'd had the bike apart over the winter. While riding it and within the powerband, I heard VERY different noises coming from under the tank (I believe). It sounded like some sort of pressure build and release when I would get on or off the throttle, respectively. Having had some strange sounds coming from automobile exhausts in the past, I added that to the list of possible causes. I've since emailed Hass, and they don't think and have never heard of this sound being generated from the removal of the HTEV.
So, here's what I've got. Something, I'm guessing the fuel pump, is making sounds when I'm in the powerband. It's loud enough that you can hear it over normal engine noise (the engine will drown it out when you get to higher revs) on accel- and deceleration. On decel, if I close the throttle completely it's quite a distinctive sound. It almost sounds like a blow-off valve or something. It's more difficult to hear on acceleration, but it's there nonetheless. At idle if I put my ear close to the tank, I can hear the pump running, which I don't believe I've heard in the past. I've taken the bike for a few rides and the sound has been consistent. I don't notice any performance loss or jerkiness which I would expect if the fuel rail wasn't adequately pressurized at all times. Quick on-off-on produces what I'd expect, a wheelie - no bogging or anything like that.
Here's what I've done. Swapped the PC3 map back to what it was before the installation (just a Jardine slipon and K&N), assuming that the new map just plain needed more fuel in certain rev ranges. No noticable difference in the sound, but noticable on performance. (I guess those things really do work!
) I've raised the tank and looked for pinched fuel and/or vent lines. Didn't see any. As I mentioned above, I confirmed from Hass that it isn't an odd-sounding exhaust noise. I haven't put the HTEV valve back on there because I'm pretty convinced that it's not the part causing the issue.
I'm not what the next step is going to be. Check with you guys first, then bring it to the dealer which is conveniently right down the street. I don't want to send it to them for repair, but have one of the guys ride it and hear what I'm hearing and offer some suggestions. I'm leaning towards a failing fuel pump - perhaps it got "damaged" (though there was no tank damage) in the highside? As of the end of last season the pump was fine however I'm not sure if they "start to fail" as opposed to "work one day, dead the next".
Whaddya think, and thanks in advance.