The "800" engine is rated at 61 BHP (62 DIN PS) at the crankshaft. Rear wheel power will be less because of losses in the primary drive (more so because it is gear driven), gearbox, and final drive.
Dyno HP will also vary a lot because of altitude and atmospheric conditions.
52 - 54 HP is about right for a stock or near stock engine at sea level, 68F and under 35% humidity if he chain is in good condition and well adjusted, and the rear tire is in good contdition and properly inflated.
On your bike, you might be able to get some 3 to 6 more HP if you work on the jetting. Only an exhaust gass analysis while on a dyno can tell you exactly.
At any rate, try adjusting the idle jets for best idle speed. On mine, I gained better than 15 MPH topend by doing this, and that translates to a good power increase.
