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  1. #1

    Pair of MSX 150's one outperforms other in major way

    I have experience with Polaris two strokes and looking to get into 4 strokes. Test rode a pair of MSX 150's both with about 190 hrs both engines seem to be running well. Owner is knowledgeable about the proper oil level and maintenance requirements but relis on a dealer for all service.

    Heres the rub, one ski runs like I would expect it to while the other ski is a bit of a dog slow out of the hole and lower top speed. My old 700 Yamaha 3 seater pulls at least as hard. But the revs are comparable in some significant chop both were revving in the low 7K area. Owner says there has always been the difference dealer always told him it was just manufacturing tolerances.

    I'm thinking it must be an issue in the pump probably needs a rebuild with new wear ring or impeller. Interested in everyone's thoughts on this and what the reasonable value for Fresh Water MSX 150's with 190 Hrs would be.

    I've read everything about the common problems with MSX but not sure of the life expectancy of well maintained examples.


  2. #2
    Redrum's Avatar
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    Owner might say they are well maintained, but what has the dealer really done with them to maintain them? Just an oil change every season? These things are so meticulous due to them only being produced for one year so not a lot to fall back on from dealer experience. That being said, the dealers are the ones with Digital Wrench and can at least diagnose these things when the sensors go wacko.

    Personally before you delve any further in these I would check the compression on the cylinders. The nickasil coating has been known to wear so you want to definitely check this. I believe you want to see anywhere from 120-150 psi, but the big key is both cylinders should be about the same number.

    As far as what you are thinking, yes I think the pump could affect your performance, but it might not be that. Reason I say this is my parent's MSX 150 is faster out of the hole than mine, but mine has a better top speed. We both just took our pumps apart this spring and they were both in great condition (the service guy we took it to raised his eyebrows at us because he said he has never seen pumps come in looking that good. They are usually beat to hell). Other issues in my mind could be a fuel filter that needs to be replaced or fuel pump not operating properly. Might want to check the fuel pressure.

    As for the longevity of these machines, I have no clue. I will say that 190 hours is getting up there. I have seen a lot of people on these forums with engine issues well before that either rebuilding or parting the thing out.

    As for the price, the banks won't let you take out a loan on these to my knowledge because the blue book value is really low (probably due to Polaris going out of the PWC business). However, these things are still valued by people. This is just my personal opinion, but if the cylinder pressures and fuel pressures check out okay, then I think if you can get both (not including trailer) for $5,000 to $6,000 you would be doing okay. It's just so hard to say with the hours they have.

  3. #3
    ripcuda's Avatar
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    Wow! 190 hours on an original MSX 150? That's rare. In the 2-stroke world, that would be reaching rebuild time. In the normal 4-stroke world... that's about half-life. But sadly the 4-stroke Weber's in the MSX 110/150 rarely get that far before suffering from one of the common killers (Nicasil failure, water pump gear failure, oil tank leaking, oil ingestion, SIFB).

    As Red suggested... ABSOLUTELY do a compression test on any MSX 110/150 you are looking to buy. Take your own good battery too, just in case. Looking for 125# - 140# and even. Nicasil failure will likely give you a low 90-110# reading. But so will a warped block. I've seen both.

    At those hours too... gotta be wondering about turbo longevity. Turbos are expensive.

    I wouldn't pay much for an original MSX 110/150... knowing all the problems that will likely develop... unless they already had the block sleeved (no more nicasil) or replated (better nicasil plating). Stock good compression and running MSX 150... would be worth about $2k *to me*... but would probably *ask* for higher in my local market... ~$3k. I'd think a pair on a trailer for $4k sounds fair... but I still don't think I'd buy them.

    *When* the Nicasil fails or the plastic waterpump drive gear goes (and likely warps the block)... you're looking at $1k min in parts to fix... and labor will be A LOT if you can't do it yourself.

    As much as I like the good running Webers I've built and played with... I really have a hard time recommending a stock one to someone... unless I know they love rebuilding their own engines and have money to burn.

    Cheers!

  4. #4
    Some more info. One ski had an overheat issue and the engine was rebuilt under extended warranty in 2007 the other one was used for demos and needed to be rebuilt before the owner took possesion of it back in 2004. Really interested in any opinions on weather performance difference is likely only a pump issue or if it could be engine related.

  5. #5
    ripcuda's Avatar
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    Well... that means it's not a true 190hrs on each existing engine... but I'd still assume the replacement engines were the stock Polaris MSX 110/150 blocks (not sleeved or replated) and thus just as likely to eventually have nicasil failure. Just sayin'.

    As for performance differences between the two? I wouldn't accept "weather" or "manufacturing tolerances" as excuses for the disparity you describe. I've had two different MSX 150, both on sleeved rebuilds... stock ECUS... both getting nearly identical top RPMs/speed... on different days. The jet pumps could contribute. Say the one ski has ride plate sealing failures and is ventilating on takeoff... where as the other doesn't. That could explain it (but is fixable). Or if one pump had a damaged stator or very worn out and the other wasn't... that could explain some top speed differences (one ski walks the other). But both should be reaching nearly the same max RPM limit (~7400-7600) and speed (gps... not dream-o-meter).

    Other issues could be fouled MAP sensors on one... maybe fuel filters... maybe plugs. But with two identical skis... you can swap parts and figure it out. That is a bonus.

    Cheers!

  6. #6
    Redrum's Avatar
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    Oh hey Rip, how likely is it for the ride plate sealing failures to happen and how do I check for that? That may be the issue I am having with my ski...

  7. #7
    ripcuda's Avatar
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    Why you need to seal your jet pump & ride plate, air leaks = jet pump ventilation

    The silicone sealant on the ride plates eventually wear out... especially along the leading edge where it mates with the intake grate and seals to the hull.

    Most find it after it gets bad enough to cause out-of-the-hole take-off issues. Engine revs up but the ski doesn't seem to getup and go like it should. On my SLT750... it got so bad that I couldn't get up on plane... so that was pretty obvious. This happened after a jetpump refresh... so it was thrusting harder than before.

    Easy way to check... with ski on trailer... put the trailer tongue on the ground... so ski nose is down. Spray some water onto the top of the ride plate around the jet pump. It should pool to the forward part of the ride plate where it seals to the hull along with the intake grate. Now let it sit and check for leaks underneath. If that pooled water is leaking out... your ride plate seal is failing.

    When this fails... it lets the jet pump suck in air (easier to suck than water) from on top the ride plate around the jet pump instead of sucking in water from below. This is correctly termed ventilation (as opposed to cavitation) and will rob you of forward thrust. Slight leaks along the ride plate will be unnoticeable as it will happen so slowly over time that you won't notice.

    Once the ski get's moving and is up on plane... there is more water getting forced in due to forward speed of ski and the scooping effect of the intake grate... so this issue is most noticeable from a stop and getting "out of the hole".

    This is to the best of my knowledge and open to correction.

    Cheers!
    Last edited by K447; 06-24-2013 at 02:27 PM. Reason: Post title

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  9. #8
    Redrum's Avatar
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    Great suggestions! Thanks!

  10. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by ripcuda View Post
    The silicone sealant on the ride plates eventually wear out... especially along the leading edge where it mates with the intake grate and seals to the hull.

    ...
    This is to the best of my knowledge and open to correction...
    Well presented, quite complete

    I might add that the ride plate water standing test (trailer tongue down) will tell you about air leaks down near or at the ride plate, but pump suction air leaks can also occur up around the sides and top of the jet pump, base and shoe.

    Essentially every joint and seam forward of the jet pump impeller must be fully sealed against air leaks.

    Even small air leaks will reduce thrust and acceleration when launching from low speeds or idle speed. Once fully on plane with forward speed the water suction forward of the impeller becomes pressurized water and the air leaks become water leaks spraying into the jet pump area above the ride plate.

  11. #10
    Redrum's Avatar
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    Thanks for the additional info Kevin. Question though. The jet pump sections did not seem sealed when I took them apart. Are you saying there is something (silicone?) that I am supposed to put between the pieces to help them seal better?

    Thanks!

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