I disassembled my boat's engine after race and found that I have broken
cylinder, crankshaft and piston ...
1. Can I use Wiseco pistons with old but
undamaged cylinders? Simply I could find only one size for Wiseco pistons
for GPR instead of 4 or 5 different sizes for stock ones.
2. Which parts I need to order from Riva to install Gas-Operated Powervalves? SD parts kit or adapter or both?

Yes you can use Wiseco, but we don't recommend it. This is due to the variance in GPR cylinders. OE or Pro-X would be your best bet. Just an FYI - You should never mix/match pistons. If you change one you should change all. With the rare exception of having just replaced all three and immediately damaging one. Also, you should never mix/match piston types. All three should be the same type.

If you are going to convert to gas-operated powervalves you will need to order part#'s RY10015-SD-KIT and RY10017. You will need one of each for each cylinder.

Thank you for soon reply.
I know that I can't use different pistons in one engine but could you explain why do you recommend ProX or OE? Wiseco pistons are light - this is a reason why I want to replace them. Of course I planned to replace all three.
I realize that there is variance in cylinders but in this case for what Wiseco make them only in one size?

This message has been edited. Last edited by: Almond,

Wiseco's expand more with heat and need greater tolerance than oe or Pro-X. A lot of people have had bad experiences with engine seizures and Wiseco's.

Pro-X are the best choice now due to a problem with the pins in the ring grooves coming out of the oe pistons.

What did you do to cause all that damage?

Good luck with your ski.

Thank you, Spud

I am not sure about reason of damage but it seems that the water was in crancase. Our races have two parts for two days: slalom at first day and CC at second. I rided first day without problems and then flushed cooling lines by fresh water through control ports (on sides of hull - do not know right term for them). Mistake was that I did not run engine at the time of flushing... Water penetrated to cylinders and crancase through cooling lines in exaust...
Next day I have my motor damaged after third circle of first heat. Guilty.