BASIC ARCHITECTURE IS the same; same bore and stroke (the 1000cc K-series originally evolved from a bored-out GSX-R750, which gave it a relatively long stroke compared to other litre sports motors), same crankcases, same cylinder head, valve angle, etc.
The GSX-S has milder cam timing, but not much milder. Inlet valve lift is reduced, exhaust valve increased, and overlap is down from the K5’s 80° to 75° – which, given the K7 engine went back to 79°, isn’t a huge difference and explains why the GSX-S motor feels a) more powerful than the claimed 146bhp, and b) so top-endy.
Valves are the same diameter but made of steel, not titanium – lower rpm means less need for low weight. Pistons are cast (not forged) designed to be 3% lighter, with…
