Engine vibration

[twandre]

This is what I was talking about when I referred to my bike as a "paint shaker"

ENGINE VIBRATION

The famous R65 engine vibration peaks at about 4500rpm.
The solutions are:

   1. Replace forward engine mount spacers (between engine and frame) with rubber spacers. These can be had for $1.50 from a BMW dealer who carries /2 parts (bore out the hole though); or $60 from Luftmeiser with some metal reinforcement. This last is known as the "Luftmeiser vibration fix." When using the rubber spacers, you can no longer torque down the engine mount nuts, so instead you need to double-nut them so they won't vibrate loose.

      Advantages: Some say the rubber spacers (/2 or Luftmeiser) absorb vibration and makes a significant difference in the bike's smoothness.

      Disadvantages: Some say handling under hard riding is compromised; the already flexy frame flexes more (after all, you can't torque the nut on the engine mount stud!). I've heard several accounts of frames cracking, possibly from not having the support it needs.

      DO NOT LOSE your stock metal spacers; not all dealers stock them and they seem to be hard to get. If your dealer can't find them on the microfiche, tell them to look under "footpeg."

   2. Get used to it. Many people eventually don't even notice it (I don't at all anymore). I noticed little vibration reduction with rubber spacers, but noticed a fairly substantial negative impact on handling. "Boxer wobble" when the bike was loaded happened sooner and annoyed me far more than the vibration.

Personally I prefer the stock metal spacers, after a trip where the (loaded) bike wobbled so badly I couldn't go faster than 70mph.

Thom

[NC Steve]

Hmmmmm, this post looks strangely very familiar..... :-?

[nhmaf]

Tuning of the engine can also affect the severity of the vibration..  After readjusting my
valve clearance and synching the carbs, what was an annoying vibration at about 60 mph
in top gear is now a bit less, and the "peak" of the vibration seems to have moved up from
60 mph to somewhere around 67 mph, where I spend less time.   Once above 72 or so, it
seems to smooth out again, or perhaps I am too busy looking for things in my path to notice !

[bpw]

Carb sync is also somewhat rpm dependant.  I just rebalanced my carbs and found that while it was a little rougher at low rpm it seems smoother at speed.  

My guess would be that it makes sense to sync the carbs for the rpm you often ride at.  Would be pretty easy to overheat an engine doing this if you werent carefull though.

  I just did guess and check until things seemed smooth.  Probably helps that I was effectivly testing under load (riding) which may be different than no load at same rpm.  I was starting from pretty close as well, this would probably take forever if you werent in the ballpark already.

edit:  I just realized Ed Miller hit this point exactly in the other thread.

[MrRiden]

I personally don't mind the [to me] minor vibration of these flat twins. Heck, twins are suppose to vibrate, aren't they? Over 5k on the tach mine turns into an electric motor, as far as smoothness goes. I do take an extra step when syncing the carbs. I balance them at Idle using the adjustment screws and then again at 3k using the cable slack adjustments. I was tempted to try the rubber mounts suggested but felt better 'bout having the engine securely mounted in the cradle.
Rich

[Justin B.]

My wife's bike has the rubber ones, I can tell no difference and will be replacing them with solid spacers if'n I ever get "'round tuit"...  Adjusting your cable sync at the RPM you are at the most will help and shouldn't affect base idle but could farkle up your off-idle response, maybe...  That's the way I do it and I've never thought it a problem.  But, I adjust my cables on the road with the engine under load so be careful if you elect to utilize this method.  The usual disclaimers apply...

[Semper Gumby]

I have the Lufty kit.  It got rid of the 4500 rpm buzz on my R65 LT.  Didn't know about the /2 fix.  Yes the bike wobbles above 75mph but I'm too heavely loaded to go much faster than that any way...I think it has always done that!  

I have a cracked forward coil mount but thats another story.  The frame seems fine after two years and 27,000 miles.

[Frank_M]

"Yes the bike wobbles above 75mph...I think it has always done that!"

So did mine...until I removed the balancing weights on the front wheel. With the last three, maybe four, tires I've had replaced (Metzlers), I told the tire guy, "Don't balance them." They argue some and must think I'm crazy, but I insist. With weights, the bike wobbled at the higher speeds. Without them, it does not. Go figure.

[Semper Gumby]

You know...I might just try it.  I've done everything else!!!

I try it on my way to Ken's when I replace the rear Macadam.

TTFN,