Just picked up 09' 1125r and engine has a distinct knocking upon start up and while idling. Not really noticeable when riding but I've got helmet on so can't really hear anything. I don't see any flakes on dipstick so thats good. My question is this normal engine noise or are there known problems that need to be fixed. The bike has 16,000mi on it owner had got it from brother so didn't know much about maintenance done on bike other than he remembers bike going in to fix electrical issues. So I'd like to know if there is any like preventative maintenance I should do on the bike before I go riding hard. The oil looks brand new it was a little more than .25 Liter low when I checked it, so added synthetic 10w-30 and it make the knocking noise a little quieter I think. I don't see any places where it would be leaking oil and took finger felt around exhaust tip there no soot. I just don't any other 1125's to compare it too. I wanna go riding but I don't wanna make something worse. Any suggestions for new owner ?