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  1. #1

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    98 to 99 xpl differences

    Just bought a good 99 xpl hull with fast bits with a very blown motor.

    Idea is to put my new 98 xpl motor in the 99 xpl hull. My 98 xpl hull and is very tired.

    What are the differences ?

    I know the drive couplers are different

    Are there performance differences between the mpems ?

    I read somewhere about a 80% throttle switch on the 99xpl which i have never seen after rebuilding my 98 xpl.

    Thanks

    Phil


  2. #2
    kecheme's Avatar
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    The main difference is driveshaft and the TPS and MPEM.

  3. #3

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    mpem, wire harneses, gauges, magneto, flywheel, pto, pto coupler, carbs, oil pump, throttle cables/oil cables, jet pump, impeller, exhaust resonator, handle bars, drive shaft -- both front and rear, thru haul fitting seal. The 98 hauls tend to be a little faster AND handle a little better than the 99's. Many 98's had pump shoes not properly installed-- required resealing

  4. #4

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    So if i'm putting my good 98 motor in my 99 hull - i need to change the pto coupler and use the 99 throttle cable that has the tps switch

    Anything else i need to get a 98 engine into a 99 hull ?

    What does the tps do ?
    Are there any performance differences between a 98 and 99 mpem ?

    Thanks Phil

  5. #5

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    99 magneto and fly wheel needs to be installed on the motor going in the 99, pick the drive line you want to use and use the whole thing, leave the throttle cable in the 99 and use it, the 99 mpem goes with the 99 and its wire harnesses, either jet pump assemblly can be used w/ all the parts that go with them-- if you use the 98 pump make sure to install the spacer washer and seal it up good

  6. #6

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    Thanks for that

    Bit concerned now - i really like how my 98 xp handles. How much difference in handling and speed does the 99 hull have compared to 98 ? Don't really want to loose any performance transplanting into a 99 hull.

    Also what is the function of the tps ?

    Does the 98 mpem have any performace differences to the 99 mpem ?

    Cheers,

    Phil

  7. #7
    retro jet's Avatar
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    I can't put my finger on it, but I thought the Sea Doo Shop or Racing manuals talked about the TPS. The way I understand it... the TPS gives the MPEM more information to control RAVEs and timing curve. RAVE evolution... exhaust pressure only diaphragm, 98 went to MPEM controlled crankcase pressure assist based on programmed RPM map in MPEM, 99 added the TPS so the MPEM can predict RPM. IE you are at 3500 RPM and hit 80% + throttle, the MPEM can open raves at a lower RPM than the 98 map because it knows it is accelerating to a point past 80% throttle.
    So the TPS improves acceleration.
    Correct me if I am wrong here guys.

    Snorkles, flaps and diaper were added in 99, but 98's were updated by dealers. Carb jetting was changed with airbox.

    Different part number impellers were used in 98 vs. 99-up, not sure of pitch, design or performance difference.

    I always thought Doo made incremental speed improvements every year based on the reviews. If they work and are in good shape, I'd use all the 99 parts I could.
    Last edited by retro jet; 09-26-2011 at 04:29 PM. Reason: what I meant in italics.

  8. #8
    retro jet's Avatar
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    pg 316 of the 2002 Shop manual PDF or section 08-04 pg 9

    Sensor controls spark advance. No mention of the RAVEs, did I make that up?

    So the MPEM tweaks the spark advance based on RPM, acceleration (change in RPM) and throttle position 80%+.

  9. #9

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    I liked the 98 timing curve in the 98 mpem, but you have to know what you are doing to mix and match the 2 skis components. The 99 MPEM w/ the tps in the throttle cable is less prone to deto-- obviously...

  10. #10
    retro jet's Avatar
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    Jim, Did they added the TPS to retard spark advance to cure a Deto problem in the '98 timing curve when going WOT?
    Right, only wholesale ignition change, no mixing and matching including the flywheel.
    Still not sure why I associated TPS with RAVEs. Maybe what I have read about TPS failures causing poor performance. Sorry about that.

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