Compression

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hal5778

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Hello All I have a 1996 Seadoo Sportster with a 717 rotax I dont have alot of history on this boat but this is what I have done and the problems I have. When I originally tried to turn the motor over it would not so I pulled the plugs and it turned over but blew out of the spark plug holes a light blue milky liquid (I assume this was a water/oil mixture). I then decided to pull the top head assembly off and noticed that there was this same liquid in both cylinders. I cleaned as much as possible changed out all Orings and reinstalled the heads using torque specs and sequence. With the plugs out the motor turns over fine and no longer is blowing any liquid out of the plug holes. When I put the plugs back in I attempted to turn the motor over and it turned briefly then stopped so I removed the plugs and once again turned the motor over with no problem and no liquid exiting. I decided to do a compression test and what I found was the front cylinder was fine with 140lbs but the back cylinder was at an extreme amount of 270lbs. I have no idea what could cause this high compression but assume this might be why it wont turn over with the plugs in. Any help in determining the problem and a method of correction will be greatly appreciated
 
Ok. First your compression is high because you still have water in the engine.

Second you have water in your engine and if it has been sitting in there for more than a day your crank bearings are already on borrowed time.

The water is down in the crankcase and when you crank it with the plugs in the crankcase pressure pulls it up onto the pistons and hydro locks it again.

You can try cranking it with your thumb over the plug hole and this will help bring the water up and out. There’s no fast or easy way to do this and you have to get most of the water out. Once you think it’s all out dump a little premix down the carbs and it will probably only pop once. The water will bridge the spark plug gap so you will have to keep cleaning them too. You have to get this thing running then run it on the water hard for more than 30 minutes to burn out all the water. Then fog it like hell before storing.

Third if your oil is blue it is wrong.
 
Thank you for your reply and help. After reading your reply I decided to pull the motor and when I started disassembly I noticed a mixture of oil and water in the crankcase like you suggested. I removed the carbs and manifold as well as the timing disc and laid the motor on its side to drain out what I could. My question is whether there is a good way to flush the crank out and if so what solution should I use to flush it out. Once again mikidymac thank you for your time and help
 
I would just use gas premixed with some oil and be careful with personal protection and explosions.
 
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