In the kawasaki line the old bayou was and still is about bulletproof, nothing fancy to go wrong.

 

There's a reason why the honda fourtrax 300 4x4 was the best selling quad ever. Reliability. I have a '84 200 that sat up for SEVEN years in my grandfather's garage. We had the carb cleaned out, new gas, battery & air filter and went riding all day. It would idle till it ran out of gas. Never quit on us once. That's my personal experience. But no matter what you buy, take care of it properly and it should last.