Sluggish acceleration above 5000 RPM

[36654]

Recently, I've noticed footpeg vibration (i.e., buzz) above 4000 rpms and sluggish acceleration above 5000.  In addition, rolling off the throttle seems abrupt.  Any thoughts?  I'm at 45,300 miles and the last dealer service was 42,000-miles last Fall.

[Oldrider51]

I assume that at the last service that the valve clearances were checked and adjusted and that they ran a diagnostics on the bike and all was okay then it is probably something small. Has the happened over time, I would run some fuel injection cleaner through it. Were the spark plugs changed?

[Ray]

Foot peg vibration can precede failure of the front end of the cardan. I'd avoid riding until I took a look. It's now a warranty item..., so....

[Motorhead1977]

^^^^ what Ray said. I checked mine at just 12,000 miles and it was just beginning to bind so I changed it out for one I bought before BMW issued the service bulletin/warranty info.

[36654]

Foot peg vibration can precede failure of the front end of the cardan. I'd avoid riding until I took a look. It's now a warranty item..., so....

The vibration appears to be engine rpm, not road speed (rear wheel RPM) dependent.

[Ray]

Foot peg vibration can precede failure of the front end of the cardan. I'd avoid riding until I took a look. It's now a warranty item..., so....

The vibration appears to be engine rpm, not road speed (rear wheel RPM) dependent.

(Or a harmonic.... Not sure you can pick up the sensation of a 4 kilohertz vibration through your feet. The changes in acceleration suggest the problem lives downstream from the engine.)

[Grumpy Goat]

(Or a harmonic.... Not sure you can pick up the sensation of a 4 kilohertz vibration through your feet. The changes in acceleration suggest the problem lives downstream from the engine.)

I agree with this, especially if all is well with the engine. Either way we won't properly diagnose it here, I'm sure.

[36654]

(Or a harmonic.... Not sure you can pick up the sensation of a 4 kilohertz vibration through your feet. The changes in acceleration suggest the problem lives downstream from the engine.)

4 to 5000 rpm is 67 to 83 hz

[36654]

(Or a harmonic.... Not sure you can pick up the sensation of a 4 kilohertz vibration through your feet. The changes in acceleration suggest the problem lives downstream from the engine.)

I agree with this, especially if all is well with the engine. Either way we won't properly diagnose it here, I'm sure.

Grumpy,

Do you have a video on how to change the shaft?  Considering my dealers 6 week wait for a service appt, I'm considering buying and installing the part.

[Grumpy Goat]

Grumpy,

Do you have a video on how to change the shaft?  Considering my dealers 6 week wait for a service appt, I'm considering buying and installing the part.

Yes I do. There is a 3-part "Driveshaft Service" series of videos detailing my first experience. There are also other videos regarding the driveshaft on this bike, with the latest being at 60k miles. They are all in the Maintenance for the BMW R12xxRS playlist on my YouTube Channel.

https://www.youtube.com/playlist?list=PL...qwnF3-6Qxh

[36654]

Grumpy,

Do you have a video on how to change the shaft?  Considering my dealers 6 week wait for a service appt, I'm considering buying and installing the part.

Yes I do. There is a 3-part "Driveshaft Service" series of videos detailing my first experience. There are also other videos regarding the driveshaft on this bike, with the latest being at 60k miles. They are all in the Maintenance for the BMW R12xxRS playlist on my YouTube Channel.

https://www.youtube.com/playlist?list=PL...qwnF3-6Qxh

At the end, video 3 of 3, when you were ready to remount the muffler, you had two coil springs.  What did they attach to?

[Grumpy Goat]

At the end, video 3 of 3, when you were ready to remount the muffler, you had two coil springs.  What did they attach to?

Short pipe that is part of the Remus system. See this video.

[36654]

At the end, video 3 of 3, when you were ready to remount the muffler, you had two coil springs.  What did they attach to?

Short pipe that is part of the Remus system. See this video.

OK.  That answers why I didn't recall any springs.

[Ray]

(Or a harmonic.... Not sure you can pick up the sensation of a 4 kilohertz vibration through your feet. The changes in acceleration suggest the problem lives downstream from the engine.)

4 to 5000 rpm is 67 to 83 hz

Yikes! I was asleep for that one.... Seconds vs. min.... Geez. 

And (correct me if I'm wrong) only half that if you are only including combustions in a four-stroke with two cylinders(?)

(You know, I recall a moment of hesitation while adding a comment on physics or engineering to one of your posts....)

[Grumpy Goat]

(You know, I recall a moment of hesitation while adding a comment on physics or engineering to one of your posts....)

You can also get the conversion on Google ...

[36654]

Yikes! I was asleep for that one.... Seconds vs. min.... Geez. 

And (correct me if I'm wrong) only half that if you are only including combustions in a four-stroke with two cylinders(?)

(You know, I recall a moment of hesitation while adding a comment on physics or engineering to one of your posts....)

Well, I had to Google proximal.  So, don't feel too bad.  

Of course, in Grumpy's video, I swear I heard him say the engine was downstream of the driveshaft.........

[Ray]

I think the Goat does that on purpose. Truly the Everyman's mechanic who refuses to edit out those wrench-dropping moments so many can identify with. Marketing genius.

[Grumpy Goat]

I think the Goat does that on purpose. Truly the Everyman's mechanic who refuses to edit out those wrench-dropping moments so many can identify with. Marketing genius.

That's part of it. The other part is ... I don't have time for navel-gazing, especially at this level of ROI, and if I catch misleading gaffes while editing, I will put an on-screen comment.

As for the "downstream" bit ... maybe it is downstream of the focal point of the video is the rear ...    JK of course ...

[36654]

BTW - Grumpy didn't find the spring or C-clip installed on the transmission output shaft when he did his DS inspection & lube. Is that something others have found?

[BobAin'tStoppin']

Right. Most bikes have no c-clip as far as I know.