Water flow for seadoo speedster

[David Gaskill]

I have a 96 speedster with twin 717's. Each engine gas 2 hose connections for flushing, one upper and one lower. Does the lower hose connections have to be closed off when in the water? I am new to jet boats but not jetski's. It would seem to me that any water pushed up by the impeller would just go out the back and not go through the engine. My engines have 155 and 154 psi in one engine and 153 and 152 in the other. What are the compression numbers for a new engine? I believe it has mineral oil in it now but I want to switch over to AMS synthetic HP Injector, any issues with that? I have already rebuilt the pumps with new wear rings, impellors, bearings and oil. I also changed all oil filters (yes I got rid of any air bubbles) and cleaned the fuel filters. Everything seems to be running awesome on land. I want to make sure that I covered all my bases before I take it out on the water. Thanks in advance for the help! By the way how fast will this thing go?

Dave
Nanaimo
British Columbia Canada

 

[seadoosnipe]

Dave, welcome!

Well, with your post, it's obvious your ready for boats. You seem to have good experience.
No, do not plug that bottom hole. That is there for water overflow. To ensure your not putting to much water pressure on the engine. If at idle, your not discharging any water through the "tell-tale" then it might be considered to pinch the hose a little from the inside. But I run the 97 Challernger with the same water system and mine is open, and the water coming from the boat's tell tale is really "squirting"........so, for now, leave it as is.
The oil, you'll really need to know what kind of oil was in or change it out completely. I'd probably stick with the Non NMMA oils, mineral, only beacause of the age of the motors. If they've been burned in on mineral, then changing that requirement, can do more harm than good.
I bought mine from the original owner and he said specifically, that he only burned synthetic, so thats what I use.