I have a '91 CBR600F2. I've owned the bike forever and am really happy with it except for the brakes. The bike has an F4i master cylinder, braided steel lines, and Galfer G1370 pads. I've removed the calipers and cleaned the pistons and their bores, with little effect. The bike requires a lot of lever effort for any real stopping power, and even when squeezing the lever hard, it doesn't stop anywhere near as well as my SV650 or SV1000. The lever is also rock hard with practically no play and I'm confident I've got it bled properly. (I use a vacuum bleeder which is pretty much foolproof.)

Both of my '03 SVs have Tokico 4-pot calipers. The 1000 came with them stock and the 650 got them after a racer on the SV forum made up some adapters to replace the stock 2-piston calipers with the 4-pot units. The 4-pot Tokicos (along with some Vesrah SRJL pads, an F4i master cylinder and steel lines) transformed the SV650 into having by far the most powerful brakes I have ever experienced. (It easily outstops my '03 GSX-R1000 which has EBC HH pads and steel lines.)

The brake caliper adapters for the SV650 were a Godsend. Unfortunately, I haven't had any luck finding a similar adapter for my CBR. I don't specifically need to use Tokico 4-piston calipers on the F2, but I'd like to swap out the calipers (and rotors, if necessary) for something with four or six pistons and much improved stopping power. Do you guys know anyone or any company that might make that particular adapter? Thanks!

Here's a not-so-good pic of the adapters on my SV650:

 

people dont make **** for these bikes anymore so i doubt it but it may be something i could make.......also it may be worth while to do an f3 brake conversion because thats when they started the floating discs.

 

EBC makes a full-floater kit and caliper re-locator kit for the F2.Used one for 4 years on my racebike,now they're on my streetbike.