I am building a streetfighter from a GSXR 750M (1991) and want to put a bigger oil cooled engine in, what should I use? Bandit 1200 or GSXR 1100? Will these fit straight in and can I use my carbs, coils etc. ??? Does the engine I use have to be a specific year?

Any A/O engine will bolt into your 91 Frame. For larger it is hard to beat the Bandit 12, but the 1127 from 89-92 GSXR 1100's and also the 1100 Katana's, as well as the 86-88 1052 from the Early GSXR 1100's will bolt in. The differences are as follows:
The Early GSXR 1052 has a stronger crank and a coil spring clutch, and screw type valve adjustment.
The 89 GSXR 1127 and 88-90 1100 Katana's have the longer stroke weaker crank but the better coil spring clutch, and screw type valve adjustment.
The 90-92 GSXR 1127 and 91 and Later Katana 1100's have the same crank but a diaphram type clutch, and Shim type valve adjustment
The Bandit 12 has the larger displacement and the Diaphram clutch, and shim type valves
All the large displacement A/O had 5 speeds that are prone to second gear trouble (pressed on gears suck) but it is easy to fix.
Thay all work well in a 750 chassis (my 88 Streetfighter has a 91 GSXR 1100 motor in it now)
Combining the lighter weight of the 750 chassis (11lbs lighter than the 1100) and better handling with the power of the 1100.
Bones

[ 05-21-2002, 09:50 PM: Message edited by: Bones_GSXR ]

Like Bones said, they all fit.
The main differences, other then technical, are that the B12 engine has an enormous amount of torque at very low revs, where as the GSX-R enigne has a lot more top-end power.
So if you want speed, use a GSX-R 11 engine; if you want easy wheelies and 'grunt', use the B12 engine.