thanks for the suggestions guys, had the bike up at the local repair shop and the mech took her for a spin, when he came back he said hes never heard the noise like that before but reckons it could be the final drive or one of the gears has lost its chrome facing, he said to book it in and he would check the final drive first as that is the least expensive option, I've used the garage for about ten years so dont think theyre tryin to rio me off, the noise is like when your driving your car and coming to a stop using the gears to slow you down and dont put your foot on the clutch until your just about stall- the noise that your getting from the gears is similar only a lot louder- but again it does'nt do it all the time?, it's very frustrating, once again thanks george