Speedster piston change?

[AndersLj]

Hello

I ran in to some problems withe my Seadoo Speedster last summer, then life got on the way and the boat has bin standing in the back yard since then.

This weekend I built the first motor bank up again and was just about to install both of them in the boat.
Before I did so I just wanted to check the second engine for minor damages and found that both pistons need replacing

So my question to you is what could cause this and do you think that I need to upsize the cylinder?
There are obvious scratches in one cylinder but there not that deep.

 

[Raven888]

That's pretty bad. You might get away with honing the cylinder\cylinders. As for the cause, could just be from a lot of hours. Are you using the correct oil and mix ratio? You don't mention what model or year it is.

 

[AndersLj]

Thanks for replying.

Yes make and model, forgot about that.
Is a Sea doo Speedster twin rotax from 95-96 don't know exact year.

It has one 657X engin (the one on the picture) and one 717 engine but wuthe stator housing from the old 657X. My guess is that some previous owner made a engine swap by some reason.

I think I found the problem and therfore the reason for my breakdown.
The oil injection was clogged, and no oil made it to the pistons.
I have cleaned the oil pump and tested it withe an electric screwdriver.

Is the oilpumps reliable or should I convert to premixed fule?


Best regards Anders

 

[Raven888]

The consensus is to stick with the oil injection.

 

[AndersLj]

The consensus is to stick with the oil injection.

Then I'll do that. Thanks

 

[Michael Hunt]

You really have 2 different engines in your Speedster?

 

[AndersLj]

You really have 2 different engines in your Speedster?

Yes i doo
To my surprise when the first one broke down the pistons was 82 mm. And not 78 mm as the 657x is supposed to be.

 

[kenneth.mccoy1]

If you look on the back right of your boat by the bilge pump exit there should be a VIN number the last two numbers are the year of your boat

 

[kenneth.mccoy1]

And if you run your fingernail along the inside of the cylinder wall and feel it catch on any groves you should get it bored out because the scratches if big enough will allow blow by

 

[AndersLj]

Yes, the last digits was 95, so that should be the production year.

I will go two the engineer shop tomorrow and let them take at look at the cylinders before I order new pistons
The summer I almost over in Sweden so it's no rush