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  1. #1

    Best msx 140 pistons(2019)

    Hello everyone, I already started a thread about msx top end kits but I found some oem cylinder instead so now Iím in search of pistons to match that. The other thread wasnít getting much activity and I figured I would start a new one since Iím talk about a new subject. Iíve been checking out some old threads for piston options and I got a the idea that oem where the best at the time in around 2010. Iím sure not much had changed but I figured I would run it across you guys and see if you have any recommendations. Iíve heard heard wsm are shorter and lower compression, spi have crappy rings, and i have net heard much about wiseco. I also found these wossner pistons, Iíve heard good things about the brand but never about in a Polaris.
    my last question is why do these msxís seem to wear out in so little time. (Mines at 90psi in all 3 cylinders with only 72hrs) Thanks.

  2. #2
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Quote Originally Posted by lovehavenfun
    ... Polaris RMK 800 years from 1999-2004 have the same Factory Polaris part number as a stock MSX 140. They are the same pistons from Polaris so I have been using these SPI brand in my own MSX 140's and all of MSX's that I work on in the shop.
    My understanding is that the SPI pistons sold to replace Polaris OEM pistons in the RMK 800 snowmobile are also the correct fit for the Polaris MSX 140 cylinders.

  3. #3
    Ok, I believe I found some oem pistons on partzilla(I’m sure they’ll contact me saying they’re not available anymore or something like that after I purchase them) but if they are still available would you reccomend that or the spi. And I had 2 other questions about things I found when disassembling my motor, does Polaris use copper high temp exhaust sealer instead of a gasket between the exhaust manifold and the jugs, or was someone already into my motor before I got it, and second do the oem pistons say MADE IN AUSTRIA and ELKO on the inside bottom.

  4. #4
    martincom's Avatar
    Join Date
    May 2010
    Brainerd, MN
    I don't have an opinion on the pistons. So I'll leave that to someone with more experience/knowledge.

    As to the no exhaust gasket gaskets and a sealant instead, yes, that is a factory assembly. Polaris had an issue with the cylinders becoming cocked/twisted when mated to the exhaust manifold. So, in part, they did away with the gaskets and began to utilize a sealant instead.

    When re-assembling, just snug the cylinder base nuts lightly. The install the exhaust manifold dry (no sealant or gaskets) and torque to spec. Then tighten the cylinder nuts to the extent possible. Remove the exhaust manifold and then complete torquing of the cylinder nuts. Do not use gaskets when installing the exhaust manifold, rather utilize Permatex 81878 Ultra Copper Maximum Temperature RTV Silicone Gasket Maker.

  5. #5
    Ok, I’m sorry I’m so needy but does anyone know where to find torque specs for these motor or an assembly manual or something along those lines.

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