'83 GSX 750 ES Piston Upgrade

[BananaSplit]

Hi All,

Curious to know if anyone had experience upgrading to oversized forged pistons? Was looking for something that would work with stock rods and gaskets. 70mm Wiseco pistons are available for GS 750 models (4188M07000), but I know the valve sizes were updated for the GSX in 83. Are the pistons interchangeable?  Was hoping someone would have suggestions on what would be ideal.

Edited May 27, 2023 by BananaSplit
still learning to spell

[Gixer1460]

The GS pistons are 2 valve and the GSX are 4 valve, so no not interchangable!

[wraith]

You can/could get a gsx750 big bore kit, think it was a 810cc kit ? But you could still use standard gaskets etc.

[BananaSplit]

2 hours ago, Gixer1460 said:

The GS pistons are 2 valve and the GSX are 4 valve, so no not interchangable!

yep, but the gs750 listings have both a 4 valve and 2 valve option as two separate kits. And yes its a 810cc kit. I am just a bit confused but I think there was a 80-83 gs750 4 valve model that might be interchangeable with the gsx 83-86?

[Gixer1460]

Prob. US list as the Yanks didn't get the 'GSX' per se - called everything GS!

[wraith]

The 80-83 and the 83-86 engines are different engines.

Also try the MTC site for kits

[BananaSplit]

so after spending two days searching the interweb, I think I have it picked out.

17 hours ago, Gixer1460 said:

Prob. US list as the Yanks didn't get the 'GSX' per se - called everything GS!

This seems to be the biggest cause of confusion. The Wiseco kit that I have settled on is the k816 70mm (+3mm OS) 10.25:1 cr. I actually came across a video of a guy rebuilding a 750 ES and caught the Wiseco piston part ID off the packaging in the background.

17 hours ago, wraith said:

The 80-83 and the 83-86 engines are different engines.

Also try the MTC site for kits

No luck here either unfortunately, all US distributors seem to quote the gs. The couple of  UK distributors mentioned the gsx.

Thanks for the help. Hopefully might help someone else looking for the same info. If anyone else knows something I don't please let me know.

[kja.busa]

Ross Pistons will make you a set, other companies like J&E will want a minimum order, but Ross will make pretty much anuthing to suit your needs.

[BananaSplit]

Thanks for the heads up, it might be easier to go with the Wiseco for now, give it works with the 750ES. Just hoping it still incorporates the TSCC system the stock pistons have.

[kja.busa]

It should do Wiseco's are good pistons, I've used them a few times.

[johnr]

just to throw in my two pennorth. you have a 750 motor, price up pistons, price up the cost of boring your block to suit. then price up the cost of a second hand gsx1100 motor. the 1100 motor will give you more power than the bored 750 motor plus the possibility of further tuning.

[coombehouse]

50 minutes ago, johnr said:

just to throw in my two pennorth. you have a 750 motor, price up pistons, price up the cost of boring your block to suit. then price up the cost of a second hand gsx1100 motor. the 1100 motor will give you more power than the bored 750 motor plus the possibility of further tuning.

Don't think the 1100 will easily fit in the 750es frame. A gsxr or bandit motor would be a much easier & cheaper option 

[BananaSplit]

well yes that would be an easier approach in some sense. What I am aiming for though, is to rebuild the 750 ES engine to its potential, while still keeping reliability in mind. Not so much just having a bigger engine. The boring is really out of necessity given there are 90k kms on this bike so far, and it has already been bored once to +1mm. Most other parts will be stock OEM where possible. Though I will be running some 34mm Mikuni RS carbs with stacks. If I throw this engine out at this stage I doubt anyone else will pick it up, and it will be the end of it's life, 30 years on. And that would be sad. 

[Duckndive]

What about GSXR 750 Pistons there 70mm

So Dependant on Pin Size and Deck Height from Pin....they maybe an option 

 

[BananaSplit]

yes potentially, but the Wiseco 816 kit seems to be a tried and tested option at 70mm. and the kit covers pins clips gasket and rings. it's not the cheapest choice but will probably be the best option in the long run. less thing to worry about in the engine overall. 

Edited June 15, 2023 by BananaSplit
spell check

[BananaSplit]

appreciate everyone chipping in to help out. when we get started I will share some images on a dedicated thread. thanks again.