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If anyone is interested in this kit make sure you get all 4 included! It wouldn't be the first time some tried to pass of 1 piston as a "kit" on ebay. It doesn't say anything about 4 pistons. If I recall correctly something similar happen to someone in this forum. Thought they were bidding on a full 4 piston kit. Turned out they only got 1. Hehe
 

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Yoshimura used Cosworth pistons in their superbikes. Those are probably the Cosworth pistons with Yoshimura's packaging. They are no longer made and very rare.

I have a new set of Cosworth pistons for the 86-87 750 superbike. They may also work in the 90-92, as well. They are complete minus the rings. The rings used were standard Suzuki. They are standard 750 bore. They're real works of art.

I may be willing to trade my set of Cosworth pistons for other Yosh rarities or sell them outright.
 

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They are nice, but they are for the smaller valves in the 86/87 head. The later heads had bigger valves so the reliefs would have to be opened up to use them with the big valve heads but after that they would work. Not much call for std bore slugs though. If they were first over I'm sure there would be a lot of people fighting over them.
 

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Discussion Starter · #7 ·
Early Yoshimura Superbike used 1mm larger intake valve with stock size exhaust..
 

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rajay said:
Early Yoshimura Superbike used 1mm larger intake valve with stock size exhaust..
That's good to know. I'll check the valve pockets. Anybody know the flow difference between the early heads versus the later heads in CFM? The older heads bolt right on without modification or additional part swappage, correct? Thanks.
 

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If you mean big valve heads (90-92) vs small valve heads (86-87) then yes, you need to change the pistons to match the bigger valves as the relief is smaller in the 86-87 pistons. That's the only thing I know of but not firsthand. I got that from a guy that raced the vintage class in AFM.
 

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Discussion Starter · #10 ·
Not that I've seen them but, every aftermarket piston I've seen come with valve reliefs oversized drom one to one a half. It is TTS, so a person could just ......ask.
 
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