Welp. Yesterday afternoon my dad and I went on a hill country ride of about 40 miles and in the final 5 miles or so the ol' GS developed an alarming rattle that sounds like it's coming from the front/top of the engine area.
Good news is it sounds like it's not coming from the bottom of the engine :) This is not a knock, or "ticking" or "tapping" or anything like that. It's not regular with engine speed, it's more of a buzz-like rattle from vibration. And I don't think it's the infamous starter clutch rattle (but it might be).
No video yet, I might make one if I can't sort this on my own in the next couple of days. Seems to be nonexistent at idle but even with the clutch in and sitting still if I rev to/over 4K rpm you hear it prominently. It really does feel like a rattle, like something bolted to the outside of the engine is loose and buzzes, then in a certain rev range mostly 4-5K it has a resonance and is much louder. It seems to go away pretty much completely over about 5-6K. Bike has no difference at all in performance, just sound. Makes the noise whether the bike is moving or not, clutch in or out. Haven't tried it in neutral.
Oh, and the odd thing is you can hear changes in the pitch of the chassis or at least front suspension movement in the rattle. In other words, if you go over a bump or grab a lot of front brake, the rattle changes/responds.
My initial thought was maybe one of the header flanges had come loose a little bit. Kind of sounds like a bit of an exhaust leak, there's a little bit of "WAH" kind of sound but that could be just a vibration/resonance. I also noticed some oil leaking (for a long time...) around the top of the cam cover. And the tachometer cable seems to be a bit loose, wondering if this could be it?
Also thinking it could be the timing chain tensioner, but most describe that noise as a "clicking" or "knocking" and this definitely is not that.
Other thing I wondered, maybe it's the steering head bearings? When the shop put a front tire on the guy said he noticed some slack and that I probably would need to replace them soonish. That was about 1K miles ago. I hadn't really noticed any issue but I suppose this could be causing this rattle. How do I check/diagnose/replace?
Anything else I should check while I'm poking around? Won't have a chance to look at it today but I'll begin digging in tomorrow.
BTW there has been some lightweight-sounding "buzz" at certain RPMs for quite a while, sounded like it's coming from the front/bottom of the tank. I always figured this was likely the bug rubber pad where the tank mounts is shot (it is), and a rattle from where the tank contacts the frame.
I'd say probably gas tank, it's easy to rule out.
Produce the buzz, then place your hand on the tank. If it goes away you know what to do.
That's the first thing I thing I tried. It doesn't appear to be the cause. But I'll look harder.
Quote from: mr72 on April 11, 2018, 05:40:48 AM
BTW there has been some lightweight-sounding "buzz" at certain RPMs for quite a while, sounded like it's coming from the front/bottom of the tank.
If you have TCP fairings, it might be worth checking the plastic under the speedo. :dunno_black:
- http://gstwins.com/gsboard/index.php?topic=72281
No fairings. Gs500e.
Have you checked the engine mounting bolts? If those are loose or the bolt snapped somehow you can get some crazy vibrations through the bike.
I checked everything I could get my hands on. The horn is mounted to a steel L-bracket and that is loose-ish. My guess now is that's the problem. I'll be able to check it later today to see if tightening that fixes it.
I've had a bolt work its way out of one of the spark plug coil packs, so there was one bolt holding it on, thing rattled up a storm. just while the engine is cool. look up in there and use a long screw driver or something to try to "wiggle" them. if one's loose could be the issue.
Well I just went out, found why the bolt holding the horn wasn't tight enough so I actually moved it to a different hole (and different screw) and tightened it good and tight.
Result: noise seems to be gone. I rode to and from the store, and the old buzz that used to be there remains but the new alarming crazy noise is gone.
WHEW!
Thanks all.