Greetings everyone. This is my first post to this forum, but I have been a regular reader since buying a pre-owned ’04 Rockster with 2900 miles. Thanks to your tips, I have had the confidence to do my own maintenance, making my first BMW one of the most economical bikes I have ever owned. It now has 75K miles and runs very rough/vibrates above 4K RPM. Average daily commute is ~4K RPM where vibration is not bad, so I continue to ride… but not as aggressively as I would like and this takes some of the fun out of riding. Here are the more recent highlights:
48K miles – replaced both primary coils (guess I didn’t notice a problem until the 2nd one failed)
60K – Autolite 3922 plugs, valve adjust, TB sync
67K – Fuel filter (WIX 33032), poly belt, cleaned air filter
70-71K – First noticed vibration above 4K RPM, decided to do nothing until the 72K tune-up.
72K – Back to NGK plugs, valve adjust, TB sync (4500 RPM on the road using TwinMax), check all coils
75K – Vibration no better/worse, try to avoid >4K RPM.
Any suggestions? If not, guess I’ll have to take it to a dealer… probably Hermy’s in Port Clinton, PA or maybe Trans-Am Cycle in Lititz, PA. The closest dealer (Main Line BMW in Wayne, PA) went out of business a couple years ago.
Very rough/vibrates above 4K RPM
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Beemeridian
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Re: Very rough/vibrates above 4K RPM
11
Last edited by Beemeridian on Sat Jun 06, 2015 6:56 pm, edited 1 time in total.
Re: Very rough/vibrates above 4K RPM
I think the problem has been solved. The poly belt had not been touched since it was installed 8K miles ago, so I checked it yesterday and it needed tightening (could be twisted past 90 degrees). Rode to work this morning and the vibration was gone. My hearing is not the best, plus I always ride with ear plugs, so that belt could have been making a racket for all I know.
Re: Very rough/vibrates above 4K RPM
Update...
After tightening the alternator belt, it must have been my imagination or wishful thinking that the vibration was gone (it wasn't). Trailored the bike to a very reputable dealer who didn't find anything wrong, so I just kept riding it. After getting 16K miles out of a set of Michelin Road Pilots, I took the wheels to my local shop to get new ones mounted and, as usual, I took the muffler off to make it easier to remove the rear wheel. After remounting the wheels, I went for a spin without the muffler and the vibration was gone! Exhaust had a mild mellow sound and was only a little louder than stock, so now there's a chrome tip where the muffler used to be. Vibration gone, better sound, and 14-1/2 pounds lighter. Sweet!
But what caused the vibration? Well, that muffler had been loose for some time. The clamp was tightened to the max, but the muffler was still loose and just hung from the rear mounting bolt and, at 4000+ RPMs, there must have been some kind of harmonic feedback from the loose muffler.
Lesson learned... tighten everything!
After tightening the alternator belt, it must have been my imagination or wishful thinking that the vibration was gone (it wasn't). Trailored the bike to a very reputable dealer who didn't find anything wrong, so I just kept riding it. After getting 16K miles out of a set of Michelin Road Pilots, I took the wheels to my local shop to get new ones mounted and, as usual, I took the muffler off to make it easier to remove the rear wheel. After remounting the wheels, I went for a spin without the muffler and the vibration was gone! Exhaust had a mild mellow sound and was only a little louder than stock, so now there's a chrome tip where the muffler used to be. Vibration gone, better sound, and 14-1/2 pounds lighter. Sweet!
But what caused the vibration? Well, that muffler had been loose for some time. The clamp was tightened to the max, but the muffler was still loose and just hung from the rear mounting bolt and, at 4000+ RPMs, there must have been some kind of harmonic feedback from the loose muffler.
Lesson learned... tighten everything!
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CycleRob
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Re: Very rough/vibrates above 4K RPM
Resonant vibrations can be destructive and annoying.
This is one for the grey matter archive -unless- the better sound and less weight has clouded the 4,000+ perception again.
This is one for the grey matter archive -unless- the better sound and less weight has clouded the 4,000+ perception again.
`09 F800ST
Member since Sept 10, 2001
"Talent, On Loan, From God" --Rush Limbaugh--
Member since Sept 10, 2001
"Talent, On Loan, From God" --Rush Limbaugh--
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Beemeridian
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Re: Very rough/vibrates above 4K RPM
11
Last edited by Beemeridian on Sat Jun 06, 2015 4:48 pm, edited 1 time in total.
Most people don't do what's right, they do what's most convenient and then repent
2015 Honda PCX150
2015 Honda PCX150
Re: Very rough/vibrates above 4K RPM
I admit, tightening the poly belt and announcing results after 1 day was a tad hasty (regretted that post on day 2). This time I waited, and after 1100 miles am sure that the loose muffler was the culprit. Didn't notice afterfire with the loose muffler, but have so-so hearing and ride with ear plugs. With the addition of a new F650GS, the Rockster is now my 2-up/rain bike and still gets a fair amount of miles.