Kawasaki CLAIMED 60hp, bike mag. tests got about 45 at the rear wheel, stock. K & N clip-on air cleaners (not fot wet or real dusty conditions) and about 3-sizes-larger main jets made a noticable difference, and if you cut out about half the exhaust baffles out, so much the better. Then grind a bevel on the front of the pistons, the width of the exhaust port, to increase scavenging time----well, I had a beautiful 1970 (charcoal grey), just like THAT, briefly, back then. Truly spooky in a straight line (K-81 Dunlops, ONLY, back then, for safety sake), but not much use for the commuting/touring-style riding I mostly did. Swapped it for an A-7 Avenger, quick enough, practical, totally reliable, if a bit wiggly.