hi marc it could be just a case were your bike is ticking over to high & the engine is starting to engage the drive to the rear wheel, if you think this is the problem then try adjusting the idle screw to lower the revs. if that does'nt work then check the other drive components for wear i.e. drivebelt, rollers & clutch, also check the clutch springs are ok. all the info you need should be in the workshop manual, hope this helps........happy motoring.
steo
June 2009