750 Short stoke pistons in Long stroke motor

[SiBag]

OK Dumb question time.

The short stroke 750 has 73mm pistons and the long stroke motor has 70mm pistons.

Is it possible to re-bore the long stroke motor to take the short stroke pistons, this should give an 815cc motor ?

I would think it would require new liners, could the short stoke liners be used or would they be too short ?

Or is it all just far too much grief ?

 

Any thoughts.

[SiBag]

Ahhhhhhh,

Done a little further reading,

Looks to be a bit more involved as the 90 - 91 pistons are 18mm pins and the 88 - 89 pistons are 20mm pins.

Reading the Frankenstein guide it looks like its a question of fitting the 88 - 89 top end onto the 90 - 91 block with a spacer.

[Swiss Toni]

Not only that, is the gudgeon pin to piston crown distance the same on both models pistons?

[Gammaboy]

13 hours ago, SiBag said:

Ahhhhhhh,

Done a little further reading,

Looks to be a bit more involved as the 90 - 91 pistons are 18mm pins and the 88 - 89 pistons are 20mm pins.

Reading the Frankenstein guide it looks like its a question of fitting the 88 - 89 top end onto the 90 - 91 block with a spacer.

ZX9 slugs are 18mm if you want to look at them. I've got a set at home that I could measure for you.

[Madb]

On 9/1/2017 at 3:10 AM, Gammaboy said:

ZX9 slugs are 18mm if you want to look at them. I've got a set at home that I could measure for you.

yes please, @Gammaboy. soz to high jack but were wondering the same. cheers.

[canamant]

No short stroke piston will fit an any long stroke crank/rod.

ZX9 piston conversion is not straightforward.  You will need to be  good with dial gauges and degree discs and know what cam timing and  VTP etc you will need for the type of engine you want.    The machining will be expensive too for 8 bores and hones, then comes  a dirty/dry build to get the deck height, block skim, custom made gasket.  I've done a few of them because of race regulations at the time and not one of them was the same so I couldn't give numbers.  Each one had to be individually measured and built  It is bloody expensive way to get a few more ccs and horses. Unless I was forced down that road I wouldn't bother unless you like the fiddling.

 

[Gammaboy]

On 9/2/2017 at 7:44 PM, Madb said:

yes please, @Gammaboy. soz to high jack but were wondering the same. cheers.

Will try to remember to have a look tonight.