BrianSM,
Show a graph!
It depends of many things as:
1)Wheel size.(SM-tyre 17" *160 runs heavy,better street-tyre 19" *110)
2)chain/sprockets.(many % lost with bad chain and sprockets)
3)A/F-ratio.(You need a O2-meter to get right)
4)Warm engine.(Warm oil and "cleaned" carb...)
5)Fuel.(old or wrong oktan)
6)........and more!!!
A KX500 stock and "blueprinted": approx..55rwhp(65hp at crank)
60 rwhp and rideable, not fantastic but sure okey!
//doordie