Ok, before you go buck wild spending money on that motor, understand that that bike and that motor are early renditions of the GS line.
I think our 8v 750s on paper were rated at about 74BHP at the crank. Im estimating that puts the horsepower to the ground at about 65HP.
Ok knowing that, and that the bike weighs 492lbs dry, you're already hampered a bit. A big bore kit, which will cost you $500 for the pistons, rings, wristpins and circlips alone, not including the cost of machining the bores we'll call it 60 bucks a hole there, so a total of another $240 bucks, you're already up to $740, and you havent even got to cams yet. We'll say those, at a streetable grind, are about 300 for the set. TO get the most out of them, you'll need degreeable sprockets, another 40 bucks each...so now, you're up to $1120, before the headwork. $600 there, you're up to $1720. A motor like that wont run for sh1t on P&C ignition, so you need a Dyna S ($120) and 3ohm coils ($120) $1960. Flatslides, as far as I know, wont mount to that head, since it uses mechanicals, so you're looking at VM29SS Smoothbores, or maybe VM33 smoothies...plan another $500 there for ones in good shape. $2460. Exhaust? $300 bucks. $2760.
Now the big bore kit for the 8v 750 from Wiseco will get you up to 844cc.
A 1979 GS850 jugs and piston set will BOLT RIGHT ON to your motor, and garner you 843cc. You can likely find a set of those ( i know someone who has a set for sale right now) for...maybe $2-300? Including the rings and wristpins and circlips probably.
You're overall HP gain out of that nearly 3000 bucks MIGHT be 50HP? Thats probably stretching it really. Lets call it 35HP at the wheel gain. So you went from 65HP at the wheel to 100HP at the wheel, on a 500lb bike. Yeah, its a bit of punch, but not alot. Lets say you weigh 150lbs. so with gas and oil in the bike (50lbs) and you, we'll call her 700lbs. Thats a 7:1 ratio. Yeah, you'll feel it, but is it worth it? Prolly not. If you want an R1, or R1 like performance, you'll be greatly disappointed. But, if you want a BAD ASS old school machine, you might think it was money well spent. Believe me, i did not nearly those kind of mods on my cafe, and im into it for 4grand including the cost of the bike. You'll find that just getting it LOOKING the way you want it will cost you quite a bit.
My advice? Buy the 79 850 jugs and pistons, a complete gasket kit, some smoothbore carbs, a nice header, and the Dyna S and coils, and call it a day. You'll still get a nice performance gain out of it, but not break the bank. The trick on a cafe is to cut weight, and gain HANDLING. Fast is great, but if it wont handle, you'll be dead real quick, or really pis$ed off, one or the other.
Do the above engine mods, install a GS1100E alu boxed swingarm, get some killer shocks, racetech or progressive fork springs, a fork brace, and some rearsets and clipons or clubman bars. Make it look the part too...you'll be deep in your pockets just doing that. And you'll be happy with the end result instead of irritated that you have a bitchin motor, but the bike wont turn.
Just my .02
TCK
EDIT: Mind you, I say all this, yet *I"M* about to spend 2 grand this winter on my 1100 putting gixxer and bandit suspension on it, and another 2 or so grand NEXT winter putting a 160ish HP motor in it! LOL. The question you really have to ask yourself is: IS IT WORTH IT TO ME? I'LL NEVER GET THE MONEY BACK OUT OF THE BIKE THAT I PUT IN, SO IF I DO THIS, ITS A KEEPER. IS IT?
:-k
