I HAVE TRIED ALL EXCEPT ENGINE,BUT AT LOW SPEEDS THERE IS A RATTLE LIKE A LOOSE EXHAUST CLAMP.tHE BIKE WORKS GREAT,EXCEPT THIS NOISE ONLY HAS 1900 KMS.THANKS

 

Remove the muffler body and shake it. If it makes a rattling noise, the welded baffle piece inside might have come off.

 

Thank you Hayashi
A friend thinks it is the fingers on the centrifugal clutch !! Ever hear of that pronlem?
I will check your ideas meantime
Again thanks

 

I think your friend has been smoking some real good stuff

Your KVF400 does not have a cetrifugal clutch! Instead, it has a plain CVT system where the drive converter squeezes on the belt as the rpm rises.

 

removed & checked the muffler,it was ok,& all fasteners are tight.My mistake friend meant the converter{my mistake}he thinks the fingers that push that converter together may be worn,the bike has only been driven at low speeds

 

The first step is to find out EXACTLY where the noise that you are hearing is coming from, exhaust, cvt, engine?