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Re: a little rough or buzz at 4250-4400 rpm

Posted: Fri Aug 11, 2017 10:30 am
by foggyhelmet
beegmouse wrote:I have this exact thing.

It's definitely a resonance. A about 4-4.5K rpm something vibrates like crazy and makes a lot of noise. It almost sounds like a fog horn.

The other topic seems to say its cause by load being put on the baring in the case of the CVT.
It can't be that as there is almost no load at 30mph, and it does it irrespective of engine braking or accelerating or cruising.

The sound is defintly behind me as I ride, I think it's coming from the airbox or fenders as, I can't explain why, but it has a plastic sound to it, not metal, not a ringing. More like a fart.

If anyone else works out whats causing it i'd love to know.
Air filter exit? Is the seal off a bit like whistling through a blade of grass?

Re: a little rough or buzz at 4250-4400 rpm

Posted: Fri Aug 11, 2017 10:33 am
by foggyhelmet
aguim wrote:Update (now that I think of it):

Like somebody else has already mentioned, that 'rough buzz' mysteriously diasappeared with
a passenger on. Also was less evident (on mine) with the spring pre-load adjusters set @ MAX.
Very good indications that the 'buzz' had something to do with the shock springs themselves.

As soon as I slid the rubber tubes over them, bingo, they quieted down.
Hmm. Good catch. I've got a party of noises happening lately, I'll have to check out the shocks. :ugeek:

Re: a little rough or buzz at 4250-4400 rpm

Posted: Sat Sep 09, 2017 11:56 pm
by mhdgraphics
It might be the CVT belt- the long stretch between the pulleys might be going into oscillation...