GS 750cafe....Big Bore project...

Ok so im starting this thread as sort of an addendum to my cafe project. I have recently procurred a second motor for my GS750 in much better cosmetic shape than my current, with only 22k on the clock. So i have an extra great running, albeit a somewhat rough looking, 750 motor. What to do what to do? BORE IT THE FUCK OUT!! hehehehe

So here's my options as of now...

1) Purchase a Wiseco bore kit, which will increase my displacement to 844cc. Thats 100 more than stock...nice increase
The Pros.... Obviously...MORE POWER.... Also included in this plan would be a set of Web .395 High lift cams and degreeable sprockets, and a heavy duty valve spring kit...total cost estimated, for parts, and machine work, about 800 bucks and i would have nice new pistons, rings, and cams.
The Cons....about 800 bucks..lol And a slight loss of cylinder wall. So far ive read no problems from this application.

2) Thanks to a lil Zook forethought, I could instead purchase a set of jugs, and head and cams from an 850 and with a lil clearance milling, it will bolt right on to my 750 bottom end.

Pros... Still more power!! Possibly cheaper than buying a bore kit. No loss of cylinder wall due to machining.
Cons...these parts will probably be used. And clearance milling could be a bit of a bitch...

Im on the fence about it...still thinking.. any suggestions or opinions welcome...otherwise..stay tuned...Pics to come shortly

AND...since there is no REAL hurry to get this motor done...i have also decided that before its done, to finish it off, it will receive a nice new set of Mikuni RS34 flatsides...ohhh im thinkin this is gonna be one raw SOB when i get it done.

Why bore it ? a GS1000 engine will fit straight in. They are shorter than the 750 as no kickstart. top rear engine mounts have to be changed to home made and the bottom front under the engine needs new plates made. The exhaust will still fit, and they can be run on 26mm 750 carbs with re jetting same size as early 1000carbs The best are the 28mm gs 1000,s carbs the slide type not cv. These will also fit the 750 but to get the best you have bore the inlet rubbers. The reason i have this info is due to having done it ( not on my own but with support and encouragement from an ex partner) was cheaper than tuning the 750 as i had wrecked the engine ( missed a gear, vroom........bang, crunch. :'((Love gs1000's). Oh ... and you need a slightly longer chain asthe front sprocket is further forward. but all the elctrics are the same and plug in, the front engine mount is the same as the 750. ;D

I"m with Alliekat on this. Forget the big bore of the 750. Go with the monster 1000, or if you are feeling up to it, the 1100E motor. This one is the ultimate of the GS motors. Bullet proof, can be bored out up to 1500cc, and is all about torque. I love mine.

Use the big motor... do it!

1000 motor is NOT a bolt in app for pre 80 GS's from what ive researched. On top of that, i have a 77, the grandpappy GS here in the states. Frame changes came in 78, and then again in 80 when it switched over to the TSCC motor (16v). I would have loved to drop in an 1000cc motor, BUT couple the above with the fact that IF you can find 1000 cc motor in decent shape, you're going to spend a mint on it. At some point i may find an 1100 for this 80 750 roller i have, as that conversion is also common (7/11 conversion, they call it...cute..heh) But in the meantime, i think this is going to be my best route of action.

TonUpSoldier said:

1000 motor is NOT a bolt in app for pre 80 GS's from what ive researched. On top of that, i have a 77, the grandpappy GS here in the states. Frame changes came in 78, and then again in 80 when it switched over to the TSCC motor (16v). I would have loved to drop in an 1000cc motor, BUT couple the above with the fact that IF you can find 1000 cc motor in decent shape, you're going to spend a mint on it. At some point i may find an 1100 for this 80 750 roller i have, as that conversion is also common (7/11 conversion, they call it...cute..heh) But in the meantime, i think this is going to be my best route of action.

Click to expand...

Might be different over there, mine was a 78 gs750e and the engine was from an early 79 1000 ( both "T" regestration over here.) my 750 had a kickstart but the 1000 engine didnt. Got the info on size and possible fitment from Heron suzuki ,( but they wouldnt say it would fit, just it was shorter and might do.) uk. The only things i had to do was make up rear top engine plates, and a bracket for the ones under the front of the engine as the bolts didnt line up. everything slse fitted , had filters though with no airbox, and four into one harris pipe, ( same as gs1000),
iwill try to find a picture. but in your area i know there was often slightly different models from th e uk ;D ;D

Yeah i have a couple of parts sitting here from the 78 model. Mine is the 77 750 "B"....some of the frame bosses are different, and they completely revamped some of the mount locations and designs of some parts, such as the rear brake MC. The B model had the res mounted to the MC, the 78 and on have a remote res...ive been trying to track down a 77 rear MC, and its a PITA

Ok miss ally I Stand corrected. After a bit more research and some more talking to a couple other 77 owners..a 1000 motor is doable. Will require a lil bit more, but not enough to deter me, and on top of that, i have a line on a 1000 motor, on the cheap. So good onya

On another note...If ever anyone ships with Forward Air...DO get insurance if available.

I Picked up my new to me motor today, crated and wrapped....I of course am stupid for not checking it before i signed off on it, but upon getting it home, i found some idiot had most likely smacked it with a fork lift. Damage is NOT severe...a split cam end cover, and the screw bosses for the cam end cover on the valve cover are snapped. Lil angry about that, but i am kinda screwed since i didnt inspect before leaving. Now i cant prove *I* didnt do it. At any rate, as i said not such a huge deal, as i have LOTS of spare cam end covers, and a new valve cover should be easy to find. IN the meantime, i have one i can borrow from this other motor for now. Will post up some pics when i get her completely uncrated. But my back is near broke, so she sits at the moment, as i moved TWO motors to my basement today, and have to move a third tomorrow...ouch...lol