Late 70's 750 converting to 1000cc?

[ToddB3]

I'm sure the 1000cc engine is a litttle bit heavier and most likely wider but I use the GS as a cruiser and camping bike, I'm just looking for some reliable grunt on the straights.

[marcovandevelde]

The GS1000 engine width and heigth is nigh on identical to the 750. They made the first GS750 oversized to take some serious punishment. What would be a nice upgrade also is to put in a 4-valve GS1100 like I did. Only other mod is the ignition (change el.unit to points, or change existing points ign. to electric) Anyway it will fit the GS750 frame easy also, even with some room to spare, as the 4 valver will be slightly shorter. All you need are new (longer) rear mounts. The weight isn't that much more than the 750 lump, maybe a couple of KG's. The benefit is the bigger torque and serious power increase, like 60 HP for the 750 to 100 HP for the 1100. Ofcourse it is always a good idea to upgrade forks, brakes and rear shocks aside wether you're fitting a bigger engine or not.

Good luck, Marco.

[Anonymous]

would my 4-into-1 fit the 1000 or 1100? I have been looking at this as an alternative...i just dont want to add this motor and have the bike handle worse then it did before...of course brakes will be upgraded as will suspension which needs it anyway.

[humhead]

The brakes & suspension are very similar. The rear brakes are identical except for the brake line. Front brakes use different calipers. The fork tubes are 2mm thicker & 17mm shorter on a 1000. The triple trees are different.
In order to mount a better front end on a 750, you will have to machine the lower triple to fit the 750 frame.
After realizing the amount of time & money necessary to do this right, I saved enough $ to buy a 1000. Now I have 2 great bikes to enjoy.

Terry

[terry]

As much as I agree with Terry that both bikes are great and if you have the room/want two bikes then it's almost economically sensible to buy the 1000/1100, fitting a 1000 engine into a 750 is a "no-brainer", the frame was very well designed and built, and can handle the more powerful engine with no problems.

Even though the 750's brakes would be laughed at nowadays, they're the same as the early GS1000 items, and if your 750 is like my 1979 "Police Special" with twin discs (and wire wheels!) then I'm sure that this set-up is more than acceptable to pull it up with the larger displacement engine.

Sadly Martin (Brit 7/11) doesn't contribute to this site much any more since he sold his Suzy's and bought a Triumph, but he could have told you everything you need to know mate, he had a GS750E with a monster GS1000 engine with a 1260cc big bore block and the best of everything inside it as his daily rider/drag racing toy, and although much modified, it started I believe like the bike you're thinking of building, and just, er, evolved.................... Anyway, food for thought. Cheers, Terry. :twisted:

[Anonymous]

Will the top-end of an GS850 fit onto a GS750 bottom end? Much cheaper then wiseco...
The heads are identical, but the pistons?

[Anonymous]

I was told that they are close to being identical and that the bottoms might need to be tweeked to get the sleeves to fit. Also the wiseco kit ups the compression ratio.

[Hap Call]

Will the top-end of an GS850 fit onto a GS750 bottom end? Much cheaper then wiseco...
The heads are identical, but the pistons?

Remember that the stroke will probably be different which means that you might have to change cranks...

Hap