anyone run Seadoos?

Compression is the big thing. The jet pumps can also be an issue. If you flip them over on a side and take the intake grate off you should be able to grab the driveshaft. It should be tight. If if flops around, bearings are shot.

I wouldn’t buy unless I could ride them or have a professional mechanic look at them. They are like a car, you can’t tell much from idling. Just because it revs up on the trailer, doesn’t mean they will run in the water.

Engines, as a rule, cannot be rebuilt by amateurs. Most buy engines from some place like SBT for about $1000. Usually large core charges. Air leaks from seals is what happens very often on old skis. No oil in air from leaks so bearings and rings burn up. Ethanol gas degrades old hoses.

They are kind of like working on a Jaguar. Not bad once you learn but, very different. Parts & tools are expensive. If he has newer motors & pumps / wear rings they might be ok. If they are original I would run away. They look nice and clean, but watercraft are often clean.