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Discussion Starter · #1 ·
So ive done a little research but really cant find a definte answer.
I have a 1996 ZX9R and I am rebuilding the motor. (Starting Knocking at end of season)


I have a set of New Old Stock 1999 ZX9R Pistons (75mm) The 94-97 use 73mm pistons.

Can I get away with just boring the cylinders +2mm and use this pistons?
 

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i don't think anyone is going to be able to answer your question. I'm assuming you are going to use your existing rods with the NOS pistons. You need to very carefully check the piston height and compare the two pistons. If the NOS pistons have valve pockets you should check whether they are compatible and match with the head.

Good luck on this.
 

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Discussion Starter · #4 ·
As far as I know the "B" and "C" ZX9's use the same I204 Rods. So I guess it boils down to piston/deck height and the valve reliefs.
 

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Consider squash area. The pistons and head work in conjunction with one another to produce a compression ratio. Not sure what that is for B models off the top of my head, but if say you use the wider C model pistons in your B, you could effectively drop the compression ratio. High compression ratios are more efficient at producing power. Altering yours to an unknown may actually hurt performance. Can you imagine how awful you'd feel going through all that trouble only to find the bike is less powerful?

Besides that, there are a couple of other things I'd suggest. First, if you're hearing knocking, you're probably hearing bearings, not pistons. Not saying it's not piston slap, but I doubt it. Second, it would be far better to sell/trade your C model pistons for B model slugs. Keep your oranges with your oranges, so to speak.
 
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