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  1. #1

    Wedge tweak on daughter's MSX 150

    Greetings, all:

    I've read a lot of posts about changing the degree of the pump wedge to create better performance. I find this interesting, while at the same time I know nothing about it. Could someone give me a quick rundown on what changes in the degree of wedge does for the ski?

    It sounds very much like what changing the motor's fixed-tilt does for an outboard motor. But I'd be interested to hear if anyone has gotten any performance improvement on any of the availabe modified wedges. I'm working an '04 MSX 150. Everything is completely stock. The one I'm interested in belongs to my daughter, while I've been working on my son's 150 for the past four or five months. My daughter's ski has never given her the first problem, which I am ecstatic about since she lives almost two hundred miles away on the coast of Maryland.

    I'm heading up there this weekend, and she made me promise to change her oil and anything else I might want to do to, as she calls it, spiff it up. She's a spped freak from a long line of speed freaks (present company included).

    Now, let me just say this: I love my daughter very much, but she is aflicited with a massive thyroid problem and weighs about 325 lbs. At this point, there's nothing she can do about it, she can't even have gastric bypass or lap band surgery, and she only gets out on her jet ski. If it's broken or not working for some other reason, she doesn't go anywhere, and that, in itself, is very bad for her. Now, I have seen MSX's with as many as three riders simultaneously, but at an obvious power loss with more weight.

    Does anyone know anything about this subject; that is, about tweaking the ski to perform better under load? She can swim very well, and she always wears her life vest, but I think she feels bad when, as a group, we must all slow down to her lower maximum speed. We don't mind, but, of course she doesn't believe this.

    Soooo, would changing the degree of the wedge get her skis nose up higher, or help her plane better?

    Thanks to all of you. Writing this has been healing in itself, as I really have no one to talk about this with.

    To end on a positive note, even though I've been working on my son's 150 for a while, we all truly love the MSX 150 ski. In the end, I think my son's problems can be tracked back to one problem: he's the worst I've ever seen for not doing regular mainenance on the ski, so I temper every repair with this knowledge, and it doesn't get me down on the ski.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Jul 2007
    near Toronto, Canada
    If you want to boost the Weber engine power, talk to desperado. He knows these engines very well, and has power boosted his own.

    There are reliability changes that can be made, but I think you have found some of those already.

    What the pump wedge does is redirect the jet thrust upwards at an angle, relative to the impeller drive line.

    The more the wedge angle increases, the more the thrust forces the rear of the ski downwards. This might sound like a bad thing, but what it really does is cause the bow of the ski to ride higher. This reduces the overall amount of the hull that is actually in the water, and it increases top speed.

    You can overdo the pump wedge angle, and then the ski just handles badly. I would think that a six or eight degree wedge would provide the best overall performance with the rider weight you have described.

    Wedges exist in angles from two degrees to eight degrees
    Six degree wedge sources

    Other small improvements can be had with aftermarket sponsons, but they are rare and hard to find.

    If the engine is having trouble reaching full peak power RPM under load, then a different impeller with a little less pitch can let the engine rev higher into its power and, and improve speed. Or boost the engine power

    Make sure the latest version of the MSX ride plate is installed. There were two versions, and the later 5631598 version works better.

    There are two different ride plates for the MSX 140 hull
    MSX 03 Rideplate - 5631257-329
    MSX 04 Rideplate - 5631598-329

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