Harmonic Vibration

I'm the owner of a 2016 R1200gs. My first "boxer" BMW. Before that I had a K1200gt. My GS has, over the last several thousand miles (it now has 22k on the odometer) developed a pronounced harmonic vibration around 4000 rpms. I call it the "4th gear, 4000 rpm vibration" because that's where it is the worst. It's so bad that it's noticeable in other gears in the 3500-4000 rpm range, just not as pronounced.
I purchased the bike with about 10,000 miles on it, and sure don't think I've noticed the harmonic vibrations until the last few thousand miles. It's pretty bad...cycling about 1 to 1.5 seconds Waaa...waaa...waaa
sending a shudder through the frame you can feel in the pegs, bars, crash bars, etc. It stops the second you pull in the clutch at speed. Unfortunately, 40mph and 4th gear is about perfect for putting through a town or commercial strip or when caught behind slower traffic. So it is like Chinese water torture. It's there in 3rd gear, awful in 4th, and noticeable in 5th. Only in 6th at highways speed does it go away (actually I think it's simply cycling so fast you can't distinguish it.)

At first I though it was fueling, or maybe valves out of time, etc. but research leads me to believe this is a normal condition of the boxer engine!!?? Read here: https://advrider.com/f/threads/harmonic-vibration.285255/

And here: https://advrider.com/f/threads/harmonic-vibration-4000-4100-rpm-on-1200-gs.734184/

So am I just wasting my time trying to chase this thing away?

I can't say for the GS but my '18 RT has no such harmonic vibration. It's very smooth, not as smooth as my GL1800 was but definitely no harmonic vibration. Interested in what others will have to offer.

I'm thinking tires. Play with your tire pressure and see if it changes anything. I had a set of Battle wings that were just like that.

If it were tires, I don't think the vibration would stop the second I pull in the clutch. I've coasted down some pretty steep hills at 35-40 mph with the clutch in and no vibrations. Can't duplicate it with the engine at idle, regardless of bikes speed.

I found this on the internet:

"ALL BMW 2 cylinder boxers vibrate at 3500-4500 RPM's that is an issue you just can't balance out. Some are worse that others & some riders are more sensitive than others."

And this:

My '00 GS has had a cyclic vibration in 4th (only) at 63 km/h for the first 78,000kms of her life so far.

The blokes who perform the major services on the bike reckon it's not abnormal.

And this:
Depending on the bike's tune, and the individual's sensitivity, ALL boxers have an amount of vibration between 3800 and 4500 RPM. It varies by bike, but almost universally falls in that range.
This is a function of the design, and has been for as long as boxer twins have existed.

This guy's really pissed! Other than the cuss words, it's not really even English: https://advrider.com/f/threads/****ing-engine-cyclic-vibration.21819/

I've put 200K on 3 wetheads and they've all done this. I can't say I've come to love it, but I've accepted it. The bike has so many wonderful characteristics that I don't find it something worth being annoyed over.

Was the harmonic vibration about the same with each one? Or was one worse than the others? Since I've only owned one, I have no other experience to compare.

motormike said:

...I've noticed the harmonic vibrations ...At first I thought it was fueling, or maybe valves out of time, etc....

Click to expand...

Have you had the valves adjusted, and the cams synch'd? Seems like that would be a good place to start. You might find that the amplitude of the vibration is reduced, and becomes tolerable. Also, go test ride another RT at a dealer, and see if another bike has the same vibration.

On my oilhead RT, I would spend a good deal of time getting the valves set with identical clearance side-to-side, and then tweaking the throttle-bodies to have good synchronization. I found that extra care spent this way would yield about 3000-5000 miles of silky smooth engine. After which, the engine would run fine, but it would be buzzy, and my hands would get numb after an hour.

My 2017 R1200RT came with some valves not-quite in spec, and with the cams not-quite in synch. After setting properly, it runs quite smoothly, and I do not notice the harmonic that you experience.

Cap

motormike said:

Was the harmonic vibration about the same with each one? Or was one worse than the others? Since I've only owned one, I have no other experience to compare.

Click to expand...

The two GSAs were about the same, one wethead, one shifthead. The wethead RT was so many miles/years ago I can't compare it to the others, but I remember that it did it.

I was going to edit my original post, but I'll say it here instead: it's not tires. I've ridden on Michelins (PR3, PR4, Road 5, Anakee 3, Anakee Adventure), Continental TKC70s, and Heidenau (K60 Scout), and it happened every time.

Yes, it's not tires. As I mentioned, the harmonic vibrations stop the second I pull in the clutch. When you do a Google search for "BMW boxer engine harmonic vibration", or "1200 LC harmonic vibration" there is a lot of responses, so it would seem to be an idiosyncrasy of the design. As I understand it, on the LC engines, the computer is "supposed" to check (and adjust as needed) throttle body sync at every engine start? Or something like that. I should have the valves checked by the next week...see if that helps any. Thanks everyone, for contributing.

Mike:

Since this is your first boxer, I suggest you let a technician, or a rider who is familiar with boxers, ride it to see if the buzz is normal. Looking at it the other way, over the years, the various boxer models have had sweet spots at various rpm ranges.

Good luck.

My 2016 has its most pronounced vibration at about 4000 rpm in 5th and 6th gear. It varies in intensity with how hard the engine is working (uphill or windy = worse, flat or slight downhill = better).

Its never so bad that its a problem, but after miles and miles at that speed/rpm I do notice it a little. That's usually when I go to Cruise Control for a few miles anyway.

I think what you're describing is normal wethead boxer behavior and you're just not used to it because you rode other types of bikes in the past.

Vibration in and of itself doesn't bother me. I've ridden Harley's, Buell's and many twins and singles that could substitute for a paint-shaker at the Home Depot. But they were "steady, continuous" vibrations, as opposed to the cyclic "Waa...waa...waa...waa...waa. harmonic vibration I'm getting from the BMW. I had a Honda VFR that did the same thing, a 1.5 to 2 second harmonic that would buzz through the frame in a wave from the rear of the bike to the front and then back. You could watch the mirrors shake, then stop, then shake again, over and over. And of course you felt it in the bars and pegs. But that was a worn chain and sprockets. The tight spot would bind and release, causing the cyclic vibration, and was easily fixed with a new chain. The GS1200 cyclic vibration at 4000 rpm "feels" very similar, but of course, there's no worn chain to blame this time. 4000 rpm's and 4th gear is right in the sweet spot when I'm in traffic or putting through a town at 40-45mph. It's maddening, and I'm afraid a deal breaker for me and BMW.

motormike said:

Vibration in and of itself doesn't bother me. I've ridden Harley's, Buell's and many twins and singles that could substitute for a paint-shaker at the Home Depot. But they were "steady, continuous" vibrations, as opposed to the cyclic "Waa...waa...waa...waa...waa. harmonic vibration I'm getting from the BMW. I had a Honda VFR that did the same thing, a 1.5 to 2 second harmonic that would buzz through the frame in a wave from the rear of the bike to the front and then back. You could watch the mirrors shake, then stop, then shake again, over and over. And of course you felt it in the bars and pegs. But that was a worn chain and sprockets. The tight spot would bind and release, causing the cyclic vibration, and was easily fixed with a new chain. The GS1200 cyclic vibration at 4000 rpm "feels" very similar, but of course, there's no worn chain to blame this time. 4000 rpm's and 4th gear is right in the sweet spot when I'm in traffic or putting through a town at 40-45mph. It's maddening, and I'm afraid a deal breaker for me and BMW.

Click to expand...

4000-rpms and 4th gear is ~62mph on my 2016 R1200RS.

36654 said:

4000-rpms and 4th gear is ~62mph on my 2016 R1200RS.

Click to expand...

The OP's GS has a shorter (higher ratio) final drive, so it doesn't go as fast as an RT/RS/R at any given RPM. That, plus the barn-door "aerodynamics", is why a GS will get worse mileage when ridden the same as an RT

motormike said:

I found this on the internet:

"ALL BMW 2 cylinder boxers vibrate at 3500-4500 RPM's that is an issue you just can't balance out. Some are worse that others & some riders are more sensitive than others."

And this:

My '00 GS has had a cyclic vibration in 4th (only) at 63 km/h for the first 78,000kms of her life so far.

The blokes who perform the major services on the bike reckon it's not abnormal.

And this:
Depending on the bike's tune, and the individual's sensitivity, ALL boxers have an amount of vibration between 3800 and 4500 RPM. It varies by bike, but almost universally falls in that range.
This is a function of the design, and has been for as long as boxer twins have existed.

This guy's really pissed! Other than the cuss words, it's not really even English: https://advrider.com/f/threads/****ing-engine-cyclic-vibration.21819/

Click to expand...

...and that was the reason why I traded my 2015 RT for a GT half way to NY from San Diego. It was vibrating my arses off of me on the desert roads doing 80-90 (which is somewhere around that rpm)....only to get stuck on the road with a 2015 GT BMW quirk....and them's the reason why I am on a 2019 Goldwing now.

I wanna get a 1250; but the prevailing engine noise being frequently reported is keeping me away from my would be then, 5th RT.

Went out on the bike today, after a service. Did the work myself, and checked the valve timing using the BMW tool. Was actually hoping the valve timing would be off in an effort to smooth out the engine, but it was absolutely spot-on. The numbers I mentioned earlier were off a little. The vibration is worst in 4th gear around 3500 to 3600 rpm, equal to 40-45 mph on the GPS. Pretty miserable motoring through a town at those speeds. I can feel it in the bars, pegs, seat, just about everywhere. Ruins what would otherwise be a fine motorcycle. Pity there seems to be no way to tune it out.

This come from the BMW R1200r forum: https://www.r1200rforum.com/threads/2015-r1200r-engine-vibration.20881/

The poster compares it to a twin-engine propeller plane with the props out of sync. I realize that won't mean much to someone that's not a multiengine pilot, but the analogy is perfect.

motormike said:

The numbers I mentioned earlier were off a little. The vibration is worst in 4th gear around 3500 to 3600 rpm, equal to 40-45 mph on the GPS. Pretty miserable motoring through a town at those speeds.

Click to expand...

Shift down and enjoy the ride. Once you identify the buzzy spots, avoid them.

@40-45 if just cruising along, you could shift either up or down and avoid that range.

PGlaves said:

Shift down and enjoy the ride. Once you identify the buzzy spots, avoid them.

Click to expand...

that's what BMW loves: consumer complacency