The 2008 GSX-R600's oversquare 599cc displacement, with 67mm bore and 42.5mm stroke, remains unchanged this year, with the high-revving screamer still displaying a 16,000 rpm redline. The new Gixxer 600 does sport some internal changes, however, to its DOHC Inline-Four mill. The Zook's Twin Swirl Combustion Chamber (TSCC) has a new shape to it, which engineers promise will "reduce shrouding of intake valves at low lift, enhancing cylinder charging and thus increasing power output." Cylinder head refinements consist of more efficient intake ports and castings with thinner, lighter walls. The TSCC's new shape combined with new forged aluminum-alloy pistons increases the compression ratio from 12.5:1 to 12.8:1.
Each cylinder head houses four titanium-alloy valves, with a pair of 27.2mm intakes and 22mm exhausts. Changes from last year's design are the valve's bucket tappets, with the intake's 26mm tappets unchanged, but the exhaust side tappets swelling from 24mm to 25mm. Suzuki claims the exhaust tappet changes "work with a cam profile designed to increase acceleration coming off corners.
