2 787 Rebuilds, First Time

[TowerDog]

Going to have to rebuild 2 787 motors, this is my first time doing a rebuild so any advice is appreciated......96 SeaDoo GTX

First motor was flooding the cylinders with oil, ski sat for 2 years prior, so I am hoping to replace all bottom end parts. I was going to order the parts from SBT since the motor was previously rebuilt by SBT a few years back by the PO. I pulled the top end off and the rings and cylinders look fine, no scoring, or any damage what so ever, just some build up on top of the pistons from the miss-firing with all of the oil in the cylinders. If I have to replace the top end I can but I already have more in this ski than I paid for it ( Which wasn't much ). Ski would run fine on the water for about 5 minutes then start popping real bad and pulled the plugs and oil would just shoot out when cranking over with the plugs out.

Second motor I bought to replace my first one, paid a couple hundred bucks for it on craigslist, thought I would get lucky, the motor came out of a sunken ski, it is an original motor from an Xp. Put the motor in started getting some minor water in the cylinders while on the hose. Put the ski in the water, it instantly flooded the whole engine with water, also while towing the ski to and from the ramp, the whole engine filled up with gas, including the counterbalance, and when I say filled, that is no exaggeration. I did rebuild the carbs with new gaskets and needle and seat valves, and ran fine with the first motor I had in there.

I know the smart thing is to send them away, but I like messing with things and I am always trying to learn. Where I boat and ski not too many people know about working on these and I would like to pick up some skills to help others. I have been messing with this ski for about 2 years, and I am ready to ride it already but not too much of a hurry I have a cabin cruiser to enjoy the water. One of these motors I want to dump some money into with the high end parts, probably going to do the second one with those. I have the manuals for both on hand so I can follow those, I hear a lot of people saying to leave it to the experts, how true is that ?

 

[Strizzo]

The first one if the compression is good you could probably just replace the crank, the second one sounds like it needs a full rebuild, but could need jugs too, unless you find a torn or broken seal in the head or base gasket. Sounds like it wasn't winterized and left out in the cold. That one likely needs a full rebuild and I might send it off because I bet it's like peeling an onion with all the crap you could find.

On the first motor, were you able to run the oil out or just never get it started? Sometimes when they sit for years the oil can build up but the seals are still ok if you run it often enough.

 

[TowerDog]

The oil would fill the cylinders while it was running and when it sat. The ski would scream down the river fine for about 5 minutes then it would start popping and bogging down, when I let off the throttle or take my first turn. Pulled the plugs and their were fouled out, would put another set in and the same thing would happen. I went through about 4 sets thinking maybe there was a just a little sitting in the motor. The ski did sit for 2 years prior and the motor was seized up I was amazed it even ran, I was trying my luck. I am going to order crank and counterbalance from SBT.

The second motor I have not tore apart it is full of gas right now ( I was a little frustrated and just walked away from it ). That one I will probably do a full rebuild anyways, cylinders and all and used all high end parts.