Year? Older as in the 400 liquid cooled 2-stroke or newer 4-stroke? The 2-stroke (my assumption) is a great motor imo... I've rebuilt a couple. First thing I would look for is oil in the counterbalance reservoir. It sets back side of engine, just in front of divorced transmission... they have a tendency to run dry and will cause a complete engine failure. That's how I got the exposure to the engine's insides! :) Otherwise, pretty bullet proof, strong motor. Make sure air filter is pretty clear or you will foul plugs like diapers in that motor. Enjoy and if you ever need parts, I might have something laying around. BTW, if it's the 4-stroke, I have no idea... never got experience with that one.
OH, forgot, make sure the boots on the strut front hubs are not torn. They will eat a cv joint if dirt gets in there. Easy enough to replace (boot) if they're torn, but not once they've ruined the joint.