The biggest changes were reserved for the cylinder head. Both intake and exhaust port shapes were reworked, with the intake ports enlarged by 10 percent and the exhaust ports opened up by 20 percent. The titanium exhaust valves themselves are 2mm larger (up to 26mm), while the 30mm titanium intake valves remain unchanged. Combustion chamber shape and compression ratio are unchanged, although the spark plugs are now iridium-tipped for more consistent spark under high-stress conditions.
Both intake and exhaust camshafts underwent some modification, with the exhaust cam getting slightly more lift than the previous generation (8.9 versus 8.3mm); intake valve lift remains identical to before. Interestingly, the '07 cam timing has slightly less overlap and is advanced a bit compared with the older-model GSX-R; while the intake cam duration is slightly less (290 versus 295 degrees), the exhaust cam duration is longer (280 versus 275 degrees). This seems like it would be more beneficial for low-end efficiency (read: emissions) than anything else, but Suzuki engineers also tweaked other internal components that both raise the power peak by 1000 rpm and give a 250-rpm-higher redline, resulting in a claimed four-percent top-end power increase.
Fuel-injection throttle bodies remain the same size at 44mm, with Suzuki's SDTV (Suzuki Dual Throttle Valve) system smoothing off-idle throttle response. The new 12-hole injectors that replace the old four-hole units not only produce a finer spray of fuel for improved combustion, but the complete components themselves are much smaller, allowing the primary injectors to be positioned at a steeper, 30-degree angle, where they can spray more directly down the intake ports for even better combustion. A new ISC (Idle Speed Control) system incorporated into the throttle bodies automatically adjusts intake airflow volume with a bypass valve under various conditions so that the engine quickly settles into its normal idle speed; the system also runs the fast idle during cold starts.
Getting the engine to spin higher rpm without lightening the reciprocating parts required some engineering tweaks to reduce mechanical losses. One way is to reduce pumping losses (as each piston moves downward, it creates backpressure in the crankcase), so the crankcase windows between each cylinder cavity were enlarged by 9mm, with each hole now measuring 48mm in diameter to allow improved crankcase ventilation. The secondary counterbalancer driven off the front of the crankshaft to help reduce vibration remains.
Exhaust gases are handled by a combination titanium/stainless steel underengine system similar to that of the GSX-R750/600. The four titanium header pipes feed into two collectors, which then lead into a stainless steel chamber underneath the rear of the engine that contains Suzuki's SET (Suzuki Exhaust Tuning) valve and larger catalyzer. (The chamber's complicated shape and the heat retained by the catalyzer prevented titanium from being used in this part of the system.) To improve exhaust flow, the new GSX-R features dual muffler canisters instead of the usual single unit, with one exiting on each side.