Boat load of options, depends on how much you want to spend, first the only difference between your motor and the 91\92 is the head
a 907cc oiler is a bad bike if done right,i.e. get the crank out to APE or Falcion, Carillo rods, port the head etc, stage 2 Yoshimura cams, alot of power to be had,you can also mate the APE big block and Head to your bottom end but then and you would Have to, Back cut the trans, Magnaflux,and blance the crank, fix the journals if need be or try to find a 1127 oiler and go from there, stock 1127's are getting hard to find though
good luck with what you decide
88-89 750's were shortstrokes (with the exception of the 89 750rr which never came stateside), 90-95 saw return to the long stroke formula (70x48.7 if i remember correctly).
all gsxr 750's up until 91 use screw-type adjusters on forked rocker arms for valve clearance adjustment.....91-92's (u.s. model years, as the rest of the world got the water pumper in 92) went to shim over buckets with individual rocker arms, and the water pumpers went to direct valve actuation (shims under buckets).
it all depends on what you want, how much you want to spend, how easily you can get parts (as karl mentioned, 1127's are fairly hard to come by), etc.
a 907 kit (is it 907 for the short strokes? i forget...) would work very well.....the short stroke's head is well suited for a larger bore (big valves and ports, etc.)...
or, if you'd rather go the drop-in route and want a whole shitload of midrange grunt, don't forget about the katana 1100 motor.....basically the 1100 mill tuned for midrange.....
I'm pretty sure the 88-90 750s were the short-stroke motors and the 91-92 were back to the original dimensions, so there is a difference between the engines, and I think most people agree the later long stroke are the best starting place (long stroke makes them easier to tune, shim valve adjusters lets it rev). I just got the APE catalog www.aperaceparts.com in the mail the other day and it's got a lot of options for these bikes, the 907 big bore looks pretty cool.
dammit you guys must have deep pockets! some of this stuff is worth twice as much as some of our bikes combined!
let's try this again... trying not to break the bank here, but i need advice on what to do for an engine for my 89 gsxr. my old slingshot is pushing 27k hard kms, the cams are worn, the carbs are sick, and i hurt something in the motor after trying to chase down my friend's tl000r
the general consenus was that rebuilding an 89 750 is not worth it. 1127 gsxr motors are scarce and hard to find in good condition. my other option was to find the best condition last-gen oil cooler, ie. a 91 750.
i'm not sure if this is possible but are any of the later water cooled engines possible to fit into the old oil cooled frame without massive mods? i'm not sure if it can be done.
1127s are getting scarce, but the earlier 1100s are still around, but you will get an old motor that needs attention just like your 750 motor now. If you don't have the money to spend on rebuilding the 750, you definately won't be able to buy a new 1100 and rebuild it. If it were me I would buy a manual, rip out the engine and do all the work I could do myself, replacing worn parts with either aftermarket items, or genuine parts. Get it professionally bored to 900cc and if the bank balance allows, get a set of flatslides, if not befriend the local bike wrecker and get a set of 38mm Cv's of a newer model (You will have to buy new intake rubbers and get the head ported to suit)
While the engine is out give he whole bike a good going over referring to the manual specs and repairing or replacing the parts that don't come up to standard. No doubt there will be a few areas the old girl will need attention if the motors shagged.
This is how I would go as I don't have the money to go rank either, just bore it out and check and replace/repair all the other parts on the bike. No use getting an 1100 motor if the rest of the bike is shagged.
I've got a 89 750 slingshot and the motor in it was shagged but i could only find a good 1985 750 which i have put in but please note there will be some mods.
When i brought the motor i was told "shit yeah it justs bolts in" which was correct but the company I got it from failed to tell me about the 85 has hydraulic clutch where the 89 had a cable clutch. Starter motors were different etc. So just keep this in mind before you spend your money on a motor and find out that you still have more to spend!
i just found a complete 91 750 longblock with all accessories and electronics for $600cdn. mileage is unknown but it did well in compression/leakdown tests. the problem is... it has no paperwork, only the seller's word that it was from an insurance write-off but the documentation was lost with time and the motor was sitting for 3 years...