Looking at what will hopefully be my first street bike this week after months of stalking craigslist. I'm a bit nervous about the power, but my dad (avid motorcyclist for 50 years) seems to think I can handle it.
Current owner is graciously allowing me to test ride it to be sure I'm comfortable before I buy it.
Anything I need to know about these or need to keep an eye/ear out for (common failures)?
Thanks 
Harnessing the power of a 550 should be within the grasp of any sensible adult. I've got an old KZ400 and while it seemed pretty peppy when I first starting riding, all I can think now is how slow it is.
Not sure how parts availability is for the Yamahas, but my '76 KZ is not supported by Kawasaki, AT ALL.
Most older Japanese bikes with the possible exception of Honda [1]have some parts availability issues, but consumables shouldn't be that much of an issue.
I don't think anything but the usual used bike checks are required if it's in good condition, otherwise I'd walk because you really don't want to restore one of these.
[1] Used to be that Honda would make you a part for an old bike if you needed it. Wasn't cheap, but they did. They don't do that anymore, though, but there is a bunch of specialists that are still well stocked for NOS parts.
Parts availability doesn't seem too bad looking at Bike Bandit and JP Cycle. Haven't checked with the local Yamaha dealer, yet.
Looking at it today!!
So super excited!
You'll be fine on a 550.... now a 600 is a different animal (built differently, I was neck&neck with 1480cc Harley over this weekend)
In reply to Grtechguy:
Thanks for the reassurance. 1.5 hours....(yep, total nerd, been watching the clock all day 
）
My dad had an 81 650 Maxim for at least 20 years. That thing was bulletproof. Normal wear items and the occasional handlebar/windscreen replacement when my brother would crash it was it.
Shaft drive, correct?
Nope, the 550 is chain driven.
Sitting on it was comfy, but the battery wouldn't hold enough of a charge to take it down the road. They're going to get the battery fully charged and I'll be able to ride it.
The front brake doesn't work at all, and it likely needs carburetor work so still not sure I really want to hassle with it. Thinking I'm going to pass on it and keep shopping 
