My bike does that too. It seemed to get better when I changed the oil, but it may be that I have tuned it out now too. I have been riding with it like this for many thousands of KM and it doesn't get any worse. I didn't hear it at all on my last trip up North or on my ride through central BC last week.

Maybe longer rides sorts it out? Not sure.

I'm thinking its clutch related.

 

I was wondering if the throttles being in need of synchronizing could also cause it ?

 

something to do with the airbox and snorkels

are the airbox and snorkels singing to you?

is a piece of debris trapped on the underside of the air filter vibrating like a reed instrument?

or is there a small hole in the exhaust system leading to resonance at 4,000 rpm?

 

I'm betting engine guards....

 

The interesting thing is that it is there at different speeds but at the same RPM... approximately 3900 to 4200.

 

Take off the guards and report back.

 

Why is it humming ?

Because it does not know the words

If its at a specific rpm then it is probably sympathetic harmonic vibration

so just start tightening stuff real close examine of the exhaust system

 

As a different take on this, I had a VFR800 that had an odd humming sound at a certain RPM and I about went nuts trying to sort it out. Previous owner had not kept up on maintenence so I had a lot to do anyway, but what ultimately fixed the sound was a new chain and sprockets. Depending on how old yours are, it is something to consider.

 

It could be the bobber. If not, replace the needle and thread.

 

It wouldn't have been the bobbin -- Singers have them, Suzukis don't.

Norton, was there some way the engine guards were mounted wrong? Will you try to put them back on?

 

I finally got around to removing the engine guards. The pulsating/humming noise is gone. Thanks for all your help !!

 

Ill bet its the type of oil your using. Switch to Dino :biggrinjester:

 

My 06 Vee did the same thing... It turns out that if the bolt that holds the two halves of the crash guard together up front aren't torqued properly (meaning it doesn't put enough compression on that tubular metal spacer between the two halves) then it will sing, hum, and make all kinds of weird rattling noises at certain unspecified RPMs.


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