1993 xp 657 engine / crank question

[JuliusCaesar]

Just picked up a 1993 xp 657 for CHEAP. Previous owner says that it needed a new rotary valve and gear, but when he replaced it, the engine doesn't turn over. When it's pulled out, the engine will turn over. My initial thought was that the crank is fubared?

This is my very first sea doo ownership. I've worked and rebuilt many snowmobiles, so i'm good around 2 strokes, just have to get my head wrapped around the PWC portion of this adventure. What would cause the engine to not turn over when new part installed and will turn over when removed?

Sorry for the newb question, just looking to get a bit of guidance. Fully expecting to tear this down to crank but some experience on this anomaly would help.

thx!

 

[DougtheSlug]

I would expect to find the rotary valve shaft or the crank itself is not true. The gears will have very tight tolerances & something is tweaked. The system is similar to the 90's Ski-doo LC engines, the main difference is the sled engine has a water pump on the opposite side that runs off the same shaft. You'll need a degree wheel to time the rotary valve after you've fixed the problem.

 

[mikidymac]

To replace the rotary shaft you have to split the cases.

Did he do that or just shove a new one in from the side?

 

[JuliusCaesar]

To replace the rotary shaft you have to split the cases.

Did he do that or just shove a new one in from the side?

The guy he bought it from said it needed a new valve and gear. He pulled the face off and tried to time it “by eye”. Didn’t work. Pulled it out and it turns over no problem. My inclination is that he wasn’t linking up the gears properly but if the case needs to be split then I’m going that deep anyways as I always like to ensure I have my fingerprints on any rebuild so I know it’s right.

Long story short is that it didn’t work for him and he put it up for sale the next day and I grabbed it for a couple hundred. The pwc looks to have been a rental at Prior Lake MN at one time and then made it up to canada. Thing was damn filthy and missing some bolts and the old exhaust gasket was never scraped off. Looks like they just put a new one right on top of the old one after they ripped it off.

There is a ton of 2 stroke oil in the bellypan. I’ll check the pump lines to ensure nothing fell off. All kinds of zip ties holding stuff together and worm clamps on shaft to PTO and exhaust hoses. It’s a project for my 14 year old to get his hands dirty on. Teaching him the ways of doing it yourself.