i would suggest using a second comp tester for comparison. you may be surprised at the variance between gauges. also, the testing procedure can factor in a few pounds as well. engine hot? cold? etc.
depending on mileage and overall condition of the engine, as mosabi mentioned a fresh top end can help considerably. if the sled is fairly low miled and seems to be in good running condition and you are comfortable with the compression test, order a high altitude head gasket from your yamaha dealer. its a thinner gasket and will bump your compression up. it would any head gasket from the mtn specific twins.
the only downside to this is you will need to run premium fuel, min 91 octane. and i would always carry some octane boost if you frequently buy gas along the trailways.