So, I'm doing a Friday after work de-stress ride through some twisties in Rancho Santa Fe (just north of SD), and quite enjoying myself. I hit redline (before valve-float, but definitely 11K on the gauge) a few times going down a longer straight-away, and after I hit the next stop sign, I noticed (as I was pulling away from the sign) that there was a pronounced vibration-type sound from the engine. After babying it home, I know these:
-Dominant at 3K rpm. Anything lower and it disappears, anything higher than 3250 or 3500, and it's gone. Not hidden by other noises, or the exhaust, but gone.
-Only on accel. This held true until I was about 5 miles from home, and then I noticed that it was making the noise on decel if I let the bike stay in that gear long enough to slow down the revs to the range specified above).
-Oil level and quality was good, I have about 4.5K on the current change/filter.
-There is no knock, no other odd noises.
-Power was good (at least as hard as I was willing to push it knowing *something* was up).
-It sounded like from the top-end, and it was a fairly "dry" noise, maybe described as metallic, but it wasn't "harsh" by any means. Sounded like a higher-in-pitch version of a car's bumper vibrating when subwoofers are hitting bass notes and the bumper isn't bolted down tightly.
Have you checked all your engine mounts and tank stuff ?
If you're very certain it isn't exterior hardware, I'd bet on chain tensioner noise. Mine has had the same odd ball sound similar to what you describe since day one. Of course, mine comes and goes.
Could be it's just time for an oil change ? I don't let mine go more than 3k miles personally.
I haven't checked that stuff, and I did do a quick on/off of my tank/plastics to remind my friend (Motofuzzle here on the board) and I how to route the fuel plumbing when getting rid of the frame-mounted petcock.
I'll do a once-over tomorrow when I've got better access to my tools, and update. It made the same noise (no better, no worse) all the way up to San Clemente today and back.
It may just be in my mind, but it seemed like there was less compression braking today, and last night after the noise appeared. It may also just be that I was taking it easy since the noise popped up and therefore using less throttle manipulations overall.
When I had this problem, it was after one of my drops and the tank got bopped off center in the front. It was jammed up against the frame, and transmitting all kinds of vibration, especially at 3-5K. I could see the tank was off center, so I gave it a thwack and it went back to resting on its rubber mount, and I never heard that sound again.
Fuel tank. Mine does the exact same thing at 3-4k.
Check the rubber bumpers and strips to see if they've worn though. ;)
Quote from: Chuck on August 04, 2007, 05:23:43 PM
When I had this problem, it was after one of my drops and the tank got bopped off center in the front. It was jammed up against the frame, and transmitting all kinds of vibration, especially at 3-5K. I could see the tank was off center, so I gave it a thwack and it went back to resting on its rubber mount, and I never heard that sound again.
+1 I had the same problem after my wreck.The tank was pushed to the left and vibrated against the frame on the right.Messed my fresh paint up. :mad: