Going to look at a bike Sunday

That's a Sweet ride. It's always a gamble as to whether you'll have problems or not on an older bike. Many people would consider 26,000 miles a lot for an older Yamaha. It would be great as a weekend/project/toy Bike but as a commuter not so much. I'd recommend a newer Honda Shadow with about 1/2 that mileage. They have self adjusting valves and are very dependable. Of course the price tag will be higher. JM2C