4k vibration

[cibet]

:dunno
I get a buzz through the grips, footpegs and left mirror at 4000 rpm in 6th. 80 mph. My bike is an '02 r1150r. Do any of you have this same vibration?

[jdiaz]

I believe this is referred to as a "sympathetic resonance." Try downshifting to fifth at that speed and see what happens.

[DarkCloud]

Please describe the vibration.

There are a lot of things that cause an oilhead to vibrate/surge. Lugging the engine, or not having enough rpm's for the ground speed is the first. Inherent engine design with the opposed cylinders is another. Both cylinders not producing the same amount of power is one you can fix. Set the valves, sych the TB's, take it to your BMW shop and have them put it on the computer.

JON

[cibet]

I can down shift to 5th and the buzzing goes away. This is one way that I cope with it when traveling. I can run comfortably @70mph in 6th or 80mph in 5th. I just have to avoid prolonged periods of 4ooo rpm in 6th. I now have over 18k miles on the bike. I have noticed an improvement in the transmission. Smoother shifting and less false neutrals shifting into 5th. The valves are set at 6/1000 intake and 12/1000 exhaust. I believe this is spec.

[jdiaz]

Its the nature of the beast. You can try to raise the harmonic vibration point by adding weight to the handlebars, or going to a heavier bar-end weight. Anything to increase the mass in the handlebar assembly.

Jon

[cibet]

Thanks Jon, Big twins vibrate BMW,s less than most. I have ridden a few K bikes. It seems that "idle" is the only time there is a noticeable buzz. Is this true?

[jdiaz]

Originally posted by albert
Thanks Jon, Big twins vibrate BMW,s less than most. I have ridden a few K bikes. It seems that "idle" is the only time there is a noticeable buzz. Is this true?
It depends upon the K bike.....I only have ownership experience with K75's and K1200's. K75's are smooth up to 80-ish, then buzz thru the handlebars. K1200's are smooth all the time, except for a slight harshness from 4700-4900rpm.

[cibet]

In 6th that should be over100 mph. On our trip to the rocket city rally, traffic on the slab was moving at 80 mph; when in Rome... Is it easy to avoid that rpm range?

[jdiaz]

Yeah, its pretty easy. 5k rpm on a K1200LT is nearly 100mph.

[hwunger]

Well, this topic made me finally join the board !

My 2001 R1150R Roadster is one fine machine, and looks the part too - but it vibrates. Part of my problem is having owned a GL1500 Gold Wing in the past - now that bike is smooth.

After learning what a boxer should feel like (and learning to appreciate it's lightness, nimbleness, and quickness) I found that new tires, bar-backs, and peg lowers all helped. But the 4K vibes are there, even after a tuneup with synch. Interestingly, 5K and 6K are not too bad, you just have to get there.

And one more thing ... 6th gears are not all created equally - my 'sport' gear gets me 3.5K at 100 km/h but I see GS's that only spin 3K at 100 km/h ... oh well.

So now I just ride it ... :-)

Horst Unger,
Victoria, BC

[shoeman]

My R1100Rt buzzes at 5000 RPM, even when everything is set perfect. I can tell I have hit the magic number ( 5000 RPM's) just by the feel, without consulting the tach. It is the nature of a bike that has not been dampened to death.