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  1. #1

    Running Double Base Gaskets to Adjust Port Timing on 1200 motor?

    Read about this trick for building a Matrix 200 - shimming up the cylinders with dual gaskets to adjust port timing to work better with triple pipes. Had a few questions hopefully someone who has experience with both the 1200 & Matrix motors can help out.

    1. Does this also apply to the regular 1200 DI motors?
    2. Do engine cases interchange between MSX140 and 1200 Marine motors?
    3. Are MSX140 gaskets made from layered steel? Would they work with the regular 1200 engine?

    Thanks all in advance!


  2. #2
    Resident electronics hacker UnityRacing's Avatar
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    1. Not sure, but I don't believe the results would be good with a DI/EMM controlling fueling.
    2. The MSX cases are clearanced for the MSX cylinders. The case to cylinder bolts are different lengths as well. There is also a difference of oiling ports on the MSX, and a machined recess for the MAG bearing retaining circlip.
    3. No, the gaskets are of a paper design. I'd use MSX gaskets with MSX cylinders/case and 'other' 1200's I would use standard 1200 gaskets.

  3. #3
    All traces of the FICHT parts have been removed, basically what I have is a 1200 long block that will be receiving the 785 carbs and electrical system.

    One of the reasons I ask is that the msx140 gasket appears to provide much more uniform clamping pressure around the cylinder ears.

    For some reason thought I read they used multi layer steel material.

  4. #4
    Resident electronics hacker UnityRacing's Avatar
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    I've never seen a Polaris watercraft, no any watercraft use a MLS base gasket.

    The standard 1200 and the MSX are very similar in design and the gaskets are similar as well. The MSX is slightly bigger so I don't know that you can use those gaskets on the standard 1200.
    No difference in clamping, they both use 4 base to case nuts to hold the jug down. In fact the location of the bolts is the same. (the cylinder sleeve and case bore are the differences)

  5. #5
    Resident electronics hacker UnityRacing's Avatar
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    What are you using for a stator? I don't think the DI stator will work for you.

  6. #6
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    if memory serves the matris used 3 base gaskets,2 pwc stockers and a snowmobile one sandwiched between the other 2.that is what made it necessary to have special domes made to compensate for the loss of compression

  7. #7
    Quote Originally Posted by UnityRacing View Post
    What are you using for a stator? I don't think the DI stator will work for you.
    Pro785 with custom stator plate to knock about 5 degrees of timing off to keep it from exploding.

  8. #8
    Quote Originally Posted by TxPro1200 View Post
    if memory serves the matris used 3 base gaskets,2 pwc stockers and a snowmobile one sandwiched between the other 2.that is what made it necessary to have special domes made to compensate for the loss of compression

    Thanks Tx,

    What thickness does that arrive at? .060"?

    Working on getting some copper gaskets made to serve this purpose. Would be great if I could send the MSX gasket as the template as it looks to be a much better design.

  9. #9
    MSX 150 guy lives on Mr. GP1800's Avatar
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    The only problem is you may kill the bottom end performance of the motor by doing this.

    What are you using for cylinders?

  10. #10
    Moderator beerdart's Avatar
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    If needed I can laser cut some for you I would need a scan of the gasket.

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