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Big Bore KitsBig Bore Kits

Big Bore Kits from Rocky Mountain ATV/MC

High quality off road big bore kits.

Latest ATV Big Bore Kits Reviews – You could win up to $500 for reviewing products!

  • Cylinder Works Big Bore Cylinder Kit

    Cylinder Works Big Bore Cylinder Kit

    Daniel in NJ

    Catastrophic Failure

    Bought this kit, install went great! Installed this and hotcams at same time. Broke in cams and cylinder as per specs. Took out for first ride and changed oil after, FOUND BROKEN WRISTPIN CIRCLIP IN OIL. Called company, they overnighted part without hesitation. Found other half in engine, removed it with magnet. Installed new ones, bike ran like a dream. 2 months in, let clutch out of a turn and the bike died on the spot with a small pop noise. Broke down engine AGAIN and found the wristpin slide out of place due to another failed circlip, the connecting rod threw the piston up into the head bending my valves and bent the connecting rod while scoring my cylinder wall at the same time. 2,000 in damage thank you

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  • Wiseco Big Bore 440 Kit

    Wiseco Big Bore 440 Kit

    TROY in CA

    Best mod ever

    This was buy far the best upgrade I did to this quad. Great fit.

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  • Dubach Racing Engine Relocation Kit

    Dubach Racing Engine Relocation Kit

    KEVIN in UT

    Easy Install

    Smooth instal.Take your time and follow the instructions.Made minor improvemen to the bike handling

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  • Athena Big Bore Kit

    Athena Big Bore Kit

    DAVID in CA

    Athena 290 big bore wr/yz

    I have ran this big bore for three years and have great success with it, makes great bottom end and mid range power. I have ran it on my 08 yz250f with a wr trans and rekluse clutch and hot cams, awesome woods bike.

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