From my experience with ignition systems on motorcycles - they are usually what is called a 'reluctor' which is a fancy name for an inductor with a magnetic core. When the tang on the flywheel (or crank mounted disk) comes close it causes a positive spike then when it has passed, a negative spike. The width of the tang determines the range of advance that can be achieved. This may be different for the latest motorcycles that have digital ignition. My experience has mainly been with two strokes like RD250s,TZ250s RGV250. I suggest you try to reverse engineer the existing ignition system before trying to change it! The digital systems have long and short tangs to determine the crank position. You'll also probably find that the OEM ignition system won't use opto couplers. In fact most automotive systems will not use optocouplers for reliability reasons.

Try the www.diy-efi.org website as there is some stuff on ignition systems for a CBR600.

Don't expect to liberate heaps of horsepower by fiddling with the ignition - the manufacturers have optimised the ignition for a broad range of conditions and fuel. Fiddle at your own risk and the late model engines won't tolerate the ignition being wrong - holed pistons are a REAL possibility. Piston broke??