"Specific RPM Vibration" Have you heard of this??

Hey all, so I got my bike back from the dealer today. I had it in for service at 1200 miles. I asked why it made this very high pitched vibration-pinging noise between 7000-8500 RPM. It is starge because it does not do it before then and then also stops once I hit 9000 RPM. My dealer assured me that it was not an engine issue and is not caused by any engine damage. He said if it was an engine problem I would hear the noise through out the rev range and it deffinetly would not stop AT 9000 RPM.

His explanation was one I have never heard before. I have taken the bike to 2 places to find out what was causing this noise and while both assured me that it WAS NOT a problem and everything is running as it should neither could give me a positive answer. They basically said " It's a bike, they vibrate, it could be one of a million things no need to worry" but finally this dealer had an explanation. He said that the engine vibrates differently at every RPM and between 7000 and 8500 the engine was vibrating against somthing and the certain movement of the engine at that RPM was causing somthing to vibrate and make a sound of a certain wave length which is why it is so high pitched. That is only what worried me, because it sounded like tinggggggggg tinggggggggg like silver rattaling together. But he seemed to know what he was talking about.

He said it is not uncommon for engines to "buzz" or " ting " at certain RPM's only. The engine ALWAYS vibrates but because at 7000-8500 RPM the vibrations were causing movement a certain way against another piece of metal it generated a sound with this wavelength and high pitchedness. Just wanted to ask you guys... Have you ever heard of somthing like this? Was this guy just trying to put my mind at ease? I ride the bike in that rev range alot and afterwards the engine is fine and it rides fine it that range it just makes this really scary noise like it's going to blow up but everywhere I take it they say " just vibration, we checked the engine it's fine, calm down" he is probably right I just am nervous because I love my baby so much. Anyway does this sound plausable and do any of you KLXers have any issues with a certain sounding vibration at a certain RPM. Thanks for all of your help everyone!

Check that all your motor mounts are tight. Don't over torque them.

Barely even broken in at 1200 miles. Go ride it.

just a stupid suggestion but my bike made a buzzing vibrating noise in the higher rpms, and we zeroed it to the factory odometer vibrating on its bracket i dont know maybe look into it???

resonance frequency(im pretty sure its called) is the problem

http://en.wikipedia.org/wiki/Resonance

basicly, its like sitting on a swing set, you can jiggle all you want and you will just sit there, but if you time your forward and backward movements you get a good swing happening.

something is lose and just at the right rpm you hit the resonance and the vibration builds up. my klx made the same noise you describe at 3.5k rpm, it turns out it was the clutch cable vibrating.

Thanks a lot matt, I really appriciate your input I was very scared for a while that my engine had some damage and I was scared to ride it between 7000-8500 RPM because I did not want to further the damage but I was getting upset because that is pretty much the engine's sweet spot and I cannot really help riding in that zone because thats where its the most fun LOL. I am so relieved to learn that it is just harmless vibration, thanks alot!

I also have a 09 klx 250 and the plastic covers on the front of the radiator

made a load bussing sound at 7500 rpms

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