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magnum upgrades mod

  1. 425 Magnum engine swap 500 HO bored 518

    Polaris Magnum
    Well after nearly 2 years away from the Forum, I'm back and finally doing the 518 HO engine swap. The original 425 bottom end has a shorter stroke than the 500 bottom, as well as a smaller piston. I was at first just going to swap the upper top end till I discovered this, so a complete engine...
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