1998 Seadoo Speedster 787 Motor Repair

[HighTrim]

I have a brand new rebuilt motor in my 1998 Speedster.

Starting at the dock, the plastic rave valve bushing threads stripped, so rave valve dropped down onto piston, scoring it and breaking piston ring.

To repair, do I need to pull carbs to get the bottom exhaust manifold bolt out? I would like to try to leave carbs on if I can. If impossible, I will have to pull off I guess.

Second, can I reuse head gasket? Or are they one time use? Sealer on it? All the gaskets were brand new when rebuilt. I didn't even finish break in before this happened. Any other parts I must change while in there? Any tips? First time on this motor.

Thanks.

 

[Jeff Walkowiak]

Who rebuilt it? and no you can not reuse a head gasket or a base gasket , you must pull the jugs off to fix a ring and you may want to be sure nothing went in the crank when the rave broke the ring, however I can't understand how that happened, the raves are supposed to be cut with the cylinders so they don't hit a ring, even all the way to the bottom they should not touch the rings .

 

[HighTrim]

I did not break any rings. I think it overheated badly, and maybe the plastic holding the rave melted/let go as a side issue?

The exhaust side of both pistons are scored badly.....the head is pitted badly as if the piston was slamming chunks of ring into it? But the rings are fine. THe motor is still seized up, so I have no idea what is going on now.

 

[Jeff Walkowiak]

It will need the head resurfaced and the jugs bored with oversized pistons etc. The big question is why did it overheat. You should not re use the head without cleaning the pits in it and resurfacing it.
I am curious as to how the head was pitted since you said a ring did not break. Was it a piece of spark plug tip or were the rod bearings bad and the piston struck the plug.
Also when you bore the jugs the raves must be in the holes to bore them also or they will catch a ring. A 787 that is not rebuilt properly is just a waste of money as it will fail within a short time and you will be dealing with the same issues and probably more And avoid forged pistons in that engine use the cast type, have the cylinders cut to match each piston and have them marked so you know what piston and rave go where.