I bought a '02 GS500e a few months ago. It was cold as F(*k out when i bought the bike, and for the price i got it at, perhaps I didnt pay enough attention to details... Anyway 3 months later, fresh oil/air filter change later, I still hear a very distinct tapping comming from the bike. It seems to comming from the front top of the case... thus my thinking its a valve issue..
Ive noticed zero loss off power, and the bike seems to be happy at any/all RPMS... but i hear this knocking that is flat annoying.... Ive put highest grade fuel in it, along with octane booster, and maybe it is a bit less now... but its hard to be sure..
Id just like to get the nasty sound gone, and allow my vance hines exhaust to be the signature sound of my bike...
Have you adjusted the valves yet?
If it's not the actual valves, then it's most likely the end play of the cams. Nothing to worry about.
Does the sound happen all the time or does it only happen when the bike is warmed up and you pull up to a stop? Mine has cam end float noise on occasion when I pull up to a stop after a big ride. A quick rev gets rid of the knock noise. It happened more when I ran 20-40w oil instead of 10-40w. After the switch to the correct grade of oil I have not heard it.
Sounds like a valve out of adjustment.