I've noticed a strange regular clunking knock on my VF500F2. It's rhythmic, but not rapid enough to be a big end - it sounds like it happens once every chain revolution, maybe twice, and only under load (accelerating, or going up hill). I can't hear it when the engine is revving in neutral. I've not had a chance to look at it closely, but I'm thinking maybe the clutch is on its way out - it only seems to engage when the lever is let right out, there is no bite anywhere else. My other thought is a chain/sprocket wear problem. Is this a known problem? Is a clutch change straightforward (I'm reasonably skilled with motor mechanics - I've stripped bike and Land-Rover engines and gearboxes before).
The clutch sympton you describe is pretty common on these bikes. This on/off type action doesn't always mean your clutch is defective, Mine is like that and the only way I could get it sorted was to purchase aftermarket adjustable levers. Not saying it isn't your clutch but if the noise is linked to you final drive chain I'd look at that first.
Nice skirt !! Even the best quality chains/sprockets are done by about 20-25,000 miles, so just replace. With a VF500, you'd need to inspect valve tips, rockers, and cam lobes frequently for signs of wear. Try a good carb synch to see if that reduces or eliminates the knock.
