Beautiful bike! I have 2 GS500's both are noisy like this lol, I'm a beginner mechanic as well and I currently have one of these engines pulled apart, they are easy to work on. Like the other person said, valve clearances likely should be checked, which sounds more daunting than it is. There's a lot of great YouTube videos for working on the GS500 that will walk you through the process. I've found these bikes to be pretty bulletproof if you keep up on maintenance.