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Offline robinogi

  • Crossrunner Junior
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  • Posts: 5
  • City / Town: llanelli
  • Country: wales
Vibrations over 3000 rpm
on: September 17, 2020, 04:24:48 PM
I have noticed in the last 2 weeks a vibration in the seat and foot pegs of my crossrunner in every gear and neutral once over 3000 rpm and gets stronger as the revs increase. It had a end of warranty check In march then due to lockdown has sat in my garage until recently. The chain was overly tight with them which I only noticed last week. Its now better after adjusting. It used to run like a dream but not anymore. Any advice On things I could look at or try I would be extremely grateful
Many thanks robinogi

Offline Haddo

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  • Bike: 15CX
  • Country: Aus.
Re: Vibrations over 3000 rpm
Reply #1 on: September 18, 2020, 07:05:38 AM
Stale fuel? My bike reacts differently to different brands of fuel same RON.

Offline Lars

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  • Bike: RC 80 - 2015
  • Country: Germany
Re: Vibrations over 3000 rpm
Reply #2 on: September 24, 2020, 07:23:20 PM
Hello Robinogi,

unfortunately I have no proper solution for you but as someone who currently is and has been in the absolute hell that new and annoying vibrations are on a the bike for the last two months the least I can do is share a bit of my thoughts about that.
As with your bike, I got mine back form the shop after vibration free silky smooth 72035 km with high frequency vibrations at around 3 to 4k rpm.
Exactly as in your case, my chain was overly tightened and by that ( I made post about that in the forum earlier ) I mean, the freeplay on the chain was 2-3 mm at best ON THE CENTRE STAND, the chain was rock solid when the bike was on the ground, I dont even want to think about how bad it must have been with me sitting on it. It resulted in a whining sound, the bike leaned right when i opened up the throttle - it was bad.

In hindsight I made the mistake to  ride for about 100 km before taking action, it honestly took me a while to figure out that it was the chain in the first place. This is when my vibration problems started.
Since that it has been around 2500 km and its not getting better.

I have looked at every other possible fault ( within my non mechanic means ), checked all visible nuts and bolts, fairings, I found a missing screw on the radiator and replaced that but to no avail.
Vibration problems are the worst possible problems to troubleshoot and nothing short of a complete dis- and reassembly of the parts touched during the service will change that.
One bolt too lose - vibrations, one bolt too tight - vibrations - one forgotten rubber washer - vibrations, one left out or improperly fit dampener - vibrations.

My personal guess is currently that the source in my case is the chain. I have had that problem 2 years ago before going on a trip, same symptoms, chain too tight, howling noise, loosened chain up, insane vibrations at 3-4 k rpm. the trip lasted around 9000 km and the vibrations only went away after about 6k of that unfortunately that was also the point when the chain started to fall apart. After getting a new one everythign was back to normal ( other things changed was new tires new oil and filter new coolant and a new clutch lever assembly for good measure )

Right now when I pull on the chain on the rear sprocket, you cant see any abnormal wear, its not super slack or antything. I gave it a good scrub, it looks like new. I looked at the sprockets, even the extremely dirty front one, everything looks normal to me but honestly in my desperation I am absolutely willed to fork out 300 EUR on a new chain kit even though it is kind of a shot in the blue. Any other source would be vastly more expensive.

Unfortunately I recently had surgery and won't be able to ride my bike for the next 3 weeks or so.

As you can see you are not alone, I can 100 % understand the frustration.

Lars 




 

Offline Crosspurpose

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Re: Vibrations over 3000 rpm
Reply #3 on: September 24, 2020, 10:34:27 PM
I do wonder whether or not if your CR was ridden far with a chain that tight it has damaged the output shaft bearing. A worn bearing would cause vibration and noise and is a typical symptom of running a chain too tight and is why it is better to err on the side of too loose. What on Earth were they thinking tightening the chain that much? You'd need to access the sprocket to determine whether it turns smoothly with no rough spots.

Offline Lars

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  • Bike: RC 80 - 2015
  • Country: Germany
Re: Vibrations over 3000 rpm
Reply #4 on: September 25, 2020, 05:18:15 AM
Hello Crosspurpose,

that is my current worst case scenario that I dont even want to think about.

Lars

Offline robinogi

  • Crossrunner Junior
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  • City / Town: llanelli
  • Country: wales
Re: Vibrations over 3000 rpm
Reply #5 on: September 25, 2020, 08:21:32 AM
Thanks for all the advice all. It annoys me that when you take it to main dealers you get this type of service.
I need to take to a local independent motorbike mechanic.
Hopefully its not something expensive.
Fingers crossed

 



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