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  1. #1
    Old but not dead
    Join Date
    Jun 2009

    Question rear cyl.low compression msx 140

    I got 2 04' msx 140's that collided with each other, must have been a proud moment in a fathers eyes . 2 sons 2 skis large lake head on , $14000.00 Nobody hurt " Priceless". anyway got the glass work done on one and took out for a sink or swim. swam fine no power 40mph toped out!!! no torque! talked to you guys here and want to say thank you, I am no rookie to wrenches just wrenhing on skis did the compression test after covering the basic air , fuel , Fire,, 120 117 and 90 looks like rear cylinder is got an issue expected to open up and see cracks, gouges, holes , dead frog , piece of rings , somthing but what I found was very nice hed appears to be flawless will do a die penatrant test on the head tommorow o rings I guess thier calling head gasket. perfect , Now Im looking at this thing and from all I see is I think this cylinder and piston can be removed with engine in ski! Can It?
    Next should I check the reeds before I pull the jugg, is it possible to lose 30#'s in the reeds ( Obviously not a 2 stroker man) but I see no indication of problems in the cylinder piston or head

    I am in the process of building moilds of the hood and upper cowlings due to the rediculas prices of the replacement parts bout 600 for a hood comeon ! I will be building carbon fiber replacements and if you know what that looks like it will set off an average ski to exceptional! and almost indistructable hope to be able to do them for under 4oo twice as nice 2/3 the price, anybody wanting to know how to do this or buy one let me know I can give you videos avilable an tech help

  2. #2
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Welcome to the Hulk

    Click here for the 2003 MSX 140 Polaris Service Manual.
    Also applies to the 2004 MSX 140.

    Are both machines showing the same symptoms?

    You certainly can remove a cylinder and piston with the engine in the hull. Be aware that the MSX 140 cylinders are Nicasil coated, which requires different repair treatment.

    Before you do that, check the fuel pressure at the schrader valve in the return fuel line. Make sure you have 20+PSI, and that the pressure stays up when the engine is revving under load (in the water).

    One method we sometimes use to run an engine under load, is to strap the ski to the trailer front and rear, and lower it down the ramp until the jet pump intake is fully submerged. Then you can run it with the seat off, and watch it operate under power.

    Make very sure the front is strapped down to the trailer, so it cannot ride up over the bow roller. You must have the tow vehicle hooked up to the trailer, and solidly braked, or the PWC can shove the whole trailer forward!

    How many hours are on these engines?

    Does the other engine have proper compression?

    Since you have a pair of these MSX 140's, you should be able to compare notes.

    Make sure you are using the specified NGK PZFR6H spark plugs - no substitutes.

    Normally, broken reeds do not significantly affect measured compression.

    Make sure the fuel injectors are properly seated and torqued onto the heads. Do not over-torque the injector retention bolts.

    If you have any combustion leakage (blackish ooze) appearing around the base of the injector, check under the top of the bracket for a large thick O-ring. If it is missing, the injector will not be able to seal against the head.

    Sometimes you can find parts less expensively from places that are parting out Polaris PWC. Often, the engine has failed, so the body parts are available.

    The MSX 140 is a newer model, and there weren't as many made, so it might take some hunting to locate a pair of hoods.

    Got any photos you can share with us?

    Have a look here for a partial list of useful notes regarding the Ficht fuel injected Polaris engines.

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