What I can tell you about these particular bikes, since we have 2 of this year and model, one finished and one just getting started... the original charging systems are total crap so I'd be very careful on checking it out. The most prevalent indicator is, wait till it's good and hot, ride it around for some miles and then shut it down. Try to restart it hot and see if it hesitates or won't start at all. If it does, you'd probably have to go the route many of us did and get rotor/stator/reg.rect replaced or rebuilt. Also, this model is the inbetween child of the '79 and '81/'82. It has '79 carbs and engine, '81 body style, '79 single front brake rotor,... in other words, if you need something, you better make sure you know which year you need cuz most sellers don't know and will sell you the wrong thing. Overall, it is a lot more expensive for carb gasket kits and other gaskets because they only used those particular carbs and engine for '79/80. It's safer to just ask for '79 in this case. It has the mechanical slide PD carbs not CV carbs. You can't just wack the throttle open. The fuel line is a bugger to keep from kinking because of how short it is and the weird angle it needs to travel to the carb. Getting the carbs in and out is a challenge.
Now, having said all of that, once you get it setup right, it goes like spit. It's a fun bike and it's a nice size for travel but a little big for around town. I just want you to know the difficulties too because the thrill of another bike can take over our perception. Since we already have them, we'll stick with the ones we've got. But knowing what we know now about this particular model and year, I wouldn't do it again. I'd go with a different bike. Sorry.