Throttle grip buzz

[DaveZ]

I recently acquired a '96 R1100RT with 28k miles on it, and absolutely love it so far....except one thing which seems really out of character. At 3800 to 4200 rpm in 5th gear (approx my favorite highway cruise speed range), I am getting a buzz/vibration thru the throttle grip that nearly makes my right thumb and fingers go numb. Thicker gloves help, but don't eliminate it. Is it a tuning issue with my bike, or is it characteristic of the breed? If so, what can be done about it? Aftermarket grips? Replace the originals, which I'm sure these are, with new OE grips from BMW?

I had a Kawasaki Concours 1100 some years ago that I ended up selling for exactly the same reason. It had a "tune-able" counterbalance shaft in its engine to counteract the same problem, but all the tuning/fiddling with it in the world did not help, so I sold it for a Ducati, which even though a twin, did not buzz the handlebars at all. I don't want to sell this RT, so will appreciate any help/experience anyone can share.

Thanks!

[ArthurKnowles]

Most likely you need to consider a monor/major service depending on how well maintained your motorcycle was prior to buying it. My RT (also a 96) has no buzz at any speed, but after purchasing it I also performed all required/recommended maintenance to bring it to a known good state.

I changed all filters, all fluids, did a valve adjustment, alternator belt replacement, new plugs, a throttle body (TB) cleaning (just cleaning the BBS didn't help), TB sync, and by the time I was finished it would hold an 1100 RPM idle and run smooth as any large opposed twin out there. That means there is still a bit of vibration at idle, but you don't feel it anywhere on the road.

The biggest bang for the buck (so to speak) to get rid of the buzz is a valve adjustment followed by a TB sync. If you can't use the Big Brass Screws (BBS) to adjust the idle as you need, then like me you will have to remove them and clean them. But once the TBs are synced, your motor will not only idle wel, it will accelerate/decelerate in sync as well. That can make a BIG difference in the vibration/buzz of the engine.

PS: My Concours (previous motorcycle) buzzed much much worse that the RT ever did. It was a much higher vibration. I damped a lot of it out with heavier bar ends, but that should not be needed on the RT. If you have a high speed vibration, it may be more suspension/wheel/tire related.

[DaveZ]

Thanks very much, Arthur! I'm really glad to hear what you have to say, especially since you can relate to my Kawi experience. I had forgotten about the handlebar ends on that one....I tried that too, at the time, but it didn't help much.

I was planning to do the maintenance anyway, as I do not know what's been done, nor when, so your comments certainly validate the need to start there. I'll let you know how it turns out, and thanks again. I'm looking forward to all the smoothness everyone raves about with this model!

Dave

[DaveZ]

Thanks again, Arthur. Over the past few evenings, I did as you suggested -- adjusted valves (way out of whack, fortunately on the loose side), cleaned the TB's and the BBS's (both filthy, esp the TB's!), adjusted the throttle cables to a perfect sync and BBS's to a perfect sync (used my old Uni-Syn tool from SU carb days), and the bike is 1,000% better! You can still feel the motor, as I would expect from any twin, but no more buzz!

Guy I bought bike from said all service was done on schedule and at the dealer -- either that's not the case or the dealer's techs are a bunch of wankers. The bike only has 28,000 on it. I can't imagine how it got so far out of whack, but it's fine now.

One last question -- how do you get the cover off the poly-belt housing to adjust the belt, without removing the exhaust? I got mine loose and out of the way enough to determine the belt was fine, but I couldn't see how you'd get it removed? Must not have been doing something right...

Thanks again for the advice.:thumb

[ArthurKnowles]

Glad to hear it is running better. Makes a big difference in how well it performs as well as idles. :)

As for service, I'd suggest checking the owners manual for service stamps or ask a BMW dealer for its history if you are really curious.

As for the alternator cover, well the best way is to remove the right hand (left when sitting on the motorcycle) shark fin. That's the triangular piece of fiaring attached to the engine block via support rod. I remove the whole rod (two bolts with spacers) and leave the shark fin attached to the rod. The bad news is you can't remove the shark fin without alwo removing the side fairing. I usually remove the lower cowl, side fairings (both), and then the alternator cover. As part of a TB sync you alreay have the fairings off anyway so it's just another 5 minutes or so.

One key piece of advice with the fairing and shark fin though, don't tighten any bolts (aside form the rod bolts on the shark fin) until you ahve all the fairing pieces on. Just put the bolts in half tight so the fairing plastic can still move. Then from the top down align the plastic and tightent he bolts all the way. I usually start with the gas tank bolts (where the side fairings meet the gas tank strip) and work my way down. I do both side fairings before the lower cowl.

[Brownie]

Glad maintenance cured the vibes........if additional smoothness if desired, Beemer Boneyard sells great foamies that slide over OEM grips...just a nice final touch......

[108625]

I have a set of those foam grips on my R1200ST. What I really like about them is that they effectively make the grip a little larger in diameter, the stockers just felt too skinny.