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I am also waiting on parts. It's been almost a month. Easy to contact before you send the money, impossible after. Red flag.

Actually, there is a thread here somewhere called cheapest pisser... you can get a box of chrome valve stems from advance auto parts for like $5. If you remove the valve stem (they will do it for you at the store) it works great as a pisser. Yes you just drill a hole, and no you don't use any...

Ok, well it'll be a SJ next. I just picked up a beat up JS550 cheap as a project. I wish I'd known beforehand what I was getting into with this 550 project, I could have already had that SJ. Full engine replacement, top end job, new pistons, new case and crank, steering and throttle cables...

Pull it apart and clean it up. They get corroded inside.

You can run windowed pistons on a piston port motor? I always thought they were for reed motors only.

Yeah I used a mapp gas torch, and fortunately it didn't crack.

How well does the Jet Power pipe work on a 440?

I don't think they did. The 550 probably did since it was rear exhaust.

Windows cut in pistons are for reed motors. Solid pistons (with the two small holes) are for piston port engines.

I just went through this, first time I ever rebuilt a jet ski engine (done motorcycles, not much different). I was apprehensive, but splitting the cases is dead simple. Remove bolts, but leave the long bolts around the starter area and other side in, but about 1/2" unscrewed. Tap them with a...

I've read the stock jet power 550 exhaust is actually pretty good even on a 440 since it's one of the longest pipes available for the 550... better would be a half pipe.

Tried everything. Tried knocking it out from the grease hole, tried splitting it with a chisel, no fin way that thing was coming out. Heat did nothing. Took it to my buddies motorcycle shop and it took us about 10 tries and 30 minutes with a 2 claw slide hammer. Lots of heat and it finally...

The standard piston port pistons have two holes on the exhaust size about 1/4" in diameter, and that's it.

You could also pull the choke instead of pump the primer.. if it gets worse its already too rich, if it suddenly starts running better, it's running lean. Rebuild the carb, and make sure you using the original spring and lever otherwise your pop-off pressure will be way off. If you don't have...

The pump in the 550SX is a different design. The load is on the pump rather than the engine bay bulkhead. The 440 hull can crack at the bulkhead under heavy load unless a bulkhead brace is installed. I'd just go ahead and try running that engine. It was only 50 bucks you don't have much to lose.

Simple way to tell... when it starts to hesitate pump the primer once. If it picks back up it's lean, if it dies it's rich.

Yeah sounds like it's running very lean. Not getting enough fuel to run in the water. Also remember cold weather will make it run a bit leaner than hot weather. Compression is a bit low, but if it runs might as well get the tuning straightened out before you do the top end. Nice ski BTW! Be...

To be honest it really doesn't matter what it is now, because the pistons are shot and you need to have the bore sized to match a new set of pistons. The cylinder is probably worn near the ports and tapered, so the cylinder will probably need to be bored again if it's not to far over already...

Oh great idea, right it's cast bronze so that would work. Thanks!!

Looks like a 440/550 bottom end with a 550 top end, bored .5 over. Looking at the pistons, you may need to have it bored again to the next size up. Top end looks worn out.