2v 750 Piston Questions

[GabrielGoes]

Hey all, I needed some assistance and would appreciate any input or advice.. I had some questions:


1. Whats the biggest known big bore kit set up i can go on a 2v 750? ( i have heard of yoshimura doing 944 i assume new sleeves would be needed? and the pistons could never be gotten)

2. I was thinking about throwing on 850 cylinders and pistons and was wondering if anyone had any experience with this (performance gains? or even worth it?)

3. I actually have a wiseco set for a kz750 and was wondering if they would go on the GS750 (wrist pins the same size)? if so would this be better than the GS850 idea?

I was looking for a quick revvy engine that is significantly faster than the stock set up im using now. I would really like to use the wiseco pistons but dont want to find out after i get in the engine that the wrist pins arent the right size.

-Thanks!

 

[Nessism]

There are several guys using 850 cylinders and pistons on their 750. That's where the safe money goes since such a mod is reasonably affordable. One could get overbore pistons for the 850 cylinder but I think you need to go custom and that means $. There are a couple members here that have built such an engine and the info on how is in the archives.

I doubt the KZ pistons would fit. Here is a copy of the KZ manual so you can investigate piston pin sizes if you so desire...http://www.750turbo.com/manuals/GPz750_Base Manual.pdf

Another option is install a GS1000 engine. It's lighter than the 750 engine and more powerful than any big bore you can put together without spending major money.

Good luck

 

[GabrielGoes]

There are several guys using 850 cylinders and pistons on their 750. That's where the safe money goes since such a mod is reasonably affordable. One could get overbore pistons for the 850 cylinder but I think you need to go custom and that means $. There are a couple members here that have built such an engine and the info on how is in the archives.

I doubt the KZ pistons would fit. Here is a copy of the KZ manual so you can investigate piston pin sizes if you so desire...http://www.750turbo.com/manuals/GPz750_Base Manual.pdf

Another option is install a GS1000 engine. It's lighter than the 750 engine and more powerful than any big bore you can put together without spending major money.

Good luck

awesome i think the 850 route is the way to go as well. I just love the kick starter so i dont want to do the 1000 route.

My plan will be to swap cylinders (hone them a bit), swap pistons (use the old wrist pins and snap ring clips), new rings and valve stem seals while i'm at it.

Anything else need to be touched for the swap to actually work seamless? Timing, valves etc?

Also what valve stem seals do you recommend (I' just want them to last) Viton, OEM, other aftermarket?

 

[Nessism]

I'm not an expert on the 750 to 850 swap and don't want to guess. Please check the archives for older threads and hopefully someone that has done it will chime in.

There are some good aftermarket viton valve stem seals that are (my opinion) some of the few aftermarket parts that are better than OEM. https://www.ebay.com/itm/SUZUKI-GS1000-GS1100-GS850-GS750-VALVE-SEALS-VITON-/300563959200

 

[uk gs nut]

Gs 750 and 850 use 16mm wrist pins, kawa are 17mm gs1000 18mm wrist pins. If you use gs850 cylinders you could go standard or get 1mm oversize from cruzinimage in Japan. There an ebay seller, I have used there piston rings and there fine.

 

[Reddog78]

Is Wiesco 750 big bore pistons in stock 850 cylinders an option? Would this be simple "drop in" given 69mm pistons? No boring expense with additional benefit of thicker cylinder wall.

 

[uk gs nut]

I had to remove a little material from crankcase mouth to get 850 cylinders on. It was not a hard job. 69mm bore is standard 850 size.

 

[GabrielGoes]

How in the world did that guy chuck I believe, have the 920cc set up on his 750