No power when ski is in water...

[Disco Adam]

This is my first post here, so hopefully I don't screw anything up.

Anyways, I work for a powersports dealer and I'm mostly into cycles. However, my boss has an '83 JS550 that is having an issue with low power in the water. He said it ran perfect years ago and then suddenly it lost power. He pulled it out of the water and never got around to fixing it. Fast forward to this season - It starts right up, has 120 psi compression in both cylinders, is getting enough fuel, and the jet pump isn't clogged, but once it hits the water, it bogs and doesn't want to get onto plane.

He sent it home with me and told me I could ride it all I want if I can get it running. I've always wanted to give riding a stand-up shot - if I have fun on this one, I may invest in a more powerful 750SX or Superjet. I'm no mechanic, but I'm fairly handy with a wrench. I am a bit new to two strokes, I've mostly wrenched on four strokes.

I hooked up the engine to a hose today and ran it, and found that the engine bay filled with water quickly. After syphoning it all out, I ran the hose again, but at a lower rate and find that water is flowing out of the rubber tube between the expansion pipe and the waterbox, which I later found out is a resonator. I quickly found a good 5 inch tear in the rubber resonator.

Is this enough to cause a severe loss in power? Do I need to replace the resonator with a new resonator or can I use some type of rubber pipe from the expansion pipe to the waterbox without sacrificing power?

Also, I did check for a twisted crank and that doesn't seem to be the case with this machine.

 

[ger87410]

An exhaust leak will totally screw everything up, yes.

I'm not sure where to get a replacement rubber pipe. Do you have a local jet ski shop?

I forget the url of the js550 parts diagram microfiche. Hopefully someone can chime in with some help there and you can atleast get a part number for what you need.

 

[Disco Adam]

An exhaust leak will totally screw everything up, yes.

I'm not sure where to get a replacement rubber pipe. Do you have a local jet ski shop?

I forget the url of the js550 parts diagram microfiche. Hopefully someone can chime in with some help there and you can atleast get a part number for what you need.

The dealership I work for is a Kawasaki dealer, so I should be able to get parts cheap. However, the season is quickly winding to an end - I'm wondering if I can improvise and replace the resonator with just a straight hose/pipe without sacrificing power.

- Adam

 

[ger87410]

U just need to get the seal back.

I don't see why any old rubber hose won't work. No telling how long it will last.

For testing, you might even be able to just use muffler tape.

I wouldn't, if I was you. I'd opt for the correct part.

Now that you know what part's broke, and you have access to a kawi dealer, finding the right part should not be an issue.

 

[tipafew]

It sounds like you are on the right track. I have blown exh. hoses and it will really choke and engine. I would just find a rubber hose as a temporary(or permanant) fix.

 

[Disco Adam]

Thanks guys. I actually posted this topic on PWCForum.com before posting here:

JS550 Low Power Questions

I just checked my thread over there again - 26 views, 0 replies. What a waste of time...

My friend's father runs a commercial marine warehouse - they distribute parts, engines, drive systems, etc. for larger vessels. He actually had some 1 1/2" rubber exhaust tube scrap laying around and cut a length of it for me free of charge. The solution should work as a permanent solution - cool. I checked on the cost of the rubber tube from Kawasaki - one half of the rubber shell of the resonator would cost $90 retail, $50 my cost - I think I'll stick with the free exhaust hose. I did find one pinhole leak in the manifold that shot a tiny spout of water onto the head, but our welder should be able to take care of that. I zip-tied a piece of cloth on there to keep it from soaking the top of the head in the mean time.

I took it down to the lake on a two place trailer with an '09 GTX Wake Pro tied down next to it (for backup in case the JS550 decided to break down out on the water). The thing runs like a champ considering it's 26 years old - the same age as me actually. I just need to learn how to ride it. I actually tested it out in heavy chop, so not the ideal conditions for learning how to ride one, but I didn't do too bad. Turning while standing was a bit of a struggle for me, but I think with some more time on it I'll get the hang of it.

Thanks again guys!