Kawasaki make much better strokers (for other markets) but the AR’s tough, reliable in 12hp form but can blow up when tuned to 25hp by amateurs – makes lots of noise just before it goes down. Check rear end, caliper and rectifier. Rust is another problem but some well sorted bikes out there, though it’s easy to buy something on the way out. Plently of used bits. Great variety of bikes out there, some of the early models renovated well.