Motorcycle Repair: clicking noise in engine, honda cb650, hydraulic tappets

Question
1984 Honda CB650, Nighthawk
I got the bike from a friend who let it sit for a while. Oil was very low. The engine makes a loud clicking noise, could it be coming from the tappets because of very little oil? They're Hydraulic Tappets. there was also a build up of carbon on the pistons what would cause that?

I would appreciate the help.

Answer
Hi Jose.
 The carbon on the pistons is quite normal, so don't worry about it for now.

 As far as the tapping noise, check your valve adjustments.  They are likely way overdue.  You will find the specs and proceedures in the repair manual.

Good luck.
FALCON