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  1. #1
    MSX 150 Power sbronemann's Avatar
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    Fellow MSX 150 Riders?

    What's up guys? Not much here. I've put about 10 hrs on my new to me MSX 150 since I bought it with 23.1 hrs. What are the max RPM's at WOT? Mine runs between 7000-7350 and never runs consistent at WOT. It always varies from those RPM's. Any input from 150 owners or techs? No lights of any kinds come on.


  2. #2
    Rocky_Road's Avatar
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    Mine is pretty constant at 7450 to 7500, on a smooth run. I have seen it go to 7700 (and immediately felt the rev limiter do its thing), on a slight chop. I am a firm believer in using the same plugs that were originally installed...Champion RC7PYCB, which I get from SparkPlugs.com.

    There are sooo many things that can affect your top rpm's (fuel grade, impeller condition, plug condition, air temperature, fuel and gear load, etc.), that is hard to pinpoint any one reason without an obvious problem, and an check engine warning.

    Looking at this one frame from a video I took (you have to click on it, to see this), I was doing the usual 7500 I mentioned above....
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    Last edited by Rocky_Road; 07-08-2008 at 06:29 PM.

  3. #3
    MSX 150 Power sbronemann's Avatar
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    I wish mine would do that! How hard are the spark plugs to change since they're coil over spark? Mine tops out at about 63-65 per factory speedo usually hitting like 7100

  4. #4
    Rocky_Road's Avatar
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    Quote Originally Posted by sbronemann View Post
    I wish mine would do that! How hard are the spark plugs to change since they're coil over spark? Mine tops out at about 63-65 per factory speedo usually hitting like 7100
    Easy as falling off a See-Poo!

    Just use a 5mm allen wrench to remove the two screws holding down each coil (the OEM tool kit has one). Pull the coil, and the attached plug boot, off of the plug. Use the correct spark plug socket (with the rubber insert) to change the plug. I use a torque wrench to tighten them to the factory spec. Apply some dieletic (sp?) grease to the inside of the plug boot, and push back on!

    The Champion plug originally called for, can be ordered from the place I mentioned above...I received 4 the other day, and they only cost around $3.85 each. My old ones that I just pulled, had around 45 hours on them, and looked way to good to have needed changeing...but the washers on these plugs are the compression style, and are not meant to be torqued a second time. I will carry the old plugs in the ski for backup, since I won't care about the washers, in the event that I need to use one out on the water.

    P.S. I have gotten in the habit of using a little anti-seize on any bolts that I remove...to insure that they will not be froze the next time I go to remove them. I would recommend a small amount on the plug threads (not too much, so it doesn't interfer with the torqueing)!
    Last edited by Rocky_Road; 07-09-2008 at 06:02 PM.

  5. #5
    desperado's Avatar
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    Stock was running 7350rpm (+- 50) @ 59.7mph GPS (which btw was 70mph on ''wishmeter'') . Now, with basic mods & +2psi boost.... running 7,750 consistent @ 65.9 GPS (1/3 gas in tank, 250ft elevation, 62F water temp and 78F outside air temperature)..... still testing different combinations.

  6. #6
    MSX 150 Power sbronemann's Avatar
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    how did you get the higher boost? Just curious

  7. #7
    desperado's Avatar
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    Quote Originally Posted by sbronemann View Post
    how did you get the higher boost? Just curious
    I'm using a complex system involving a parallel mechanical boost controller activated in open loop only with a time delay timer to defeat the built-in ETB boost spike controls.
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  8. #8
    MSX 150 Power sbronemann's Avatar
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    Where would you get something like that and what would be the cost of something of that type? Just curious. Mine is just bone stock, no mods at all.

  9. #9
    Rocky_Road's Avatar
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    Quote Originally Posted by desperado View Post
    I'm using a complex system involving a parallel mechanical boost controller activated in open loop only with a time delay timer to defeat the built-in ETB boost spike controls.
    You just won the Work Around Award for 2008! How the heck did you come up with this??? What brand is the auxillary boost controller?

    Something else...my decal is missing from the top of the oil tank. I have always wondered just what it says! Do you mind...?

  10. #10
    desperado's Avatar
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    Quote Originally Posted by sbronemann View Post
    Where would you get something like that and what would be the cost of something of that type? Just curious. Mine is just bone stock, no mods at all.
    This is my own design, it is not commercially available. Around $300 in parts.

    I intend to send the design schematic to Randy at Watcon in recognition to his outstanding help in sending me a bunch of stuff to try and test..... impellers (5 in total!!!), wedges, cone extensions, etc, etc, etc.... I'm having a lot of fun testing different combinations and I will post details on how different parts/setups perform. I will let Randy decide if he wants to sell the design or not.

    I'm trying to get to 68mph..... the more I test, the more I believe this will be quite difficult to achieve. For testing purposes, I'm running a mix of 100LL avgas and premium unleaded and rail fuel pressure of +12psi over stock (mandatory with additional boost). Picture below shows rising rate ajustable fuel pressure regulator.
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