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Big Bore KitsBig Bore Kits

Dirt Bike Big Bore Kits

Every rider craves more power from their dirt bike, more torque to pull from. Modifying your top end with an aftermarket big bore kit can be a fairly easy way to deliver the power that you’re after by increasing torque and horsepower to give you noticeable power gains through all ranges.

Aftermarket big bore kits include larger pistons and cylinders which typically increase the engine size by around 3 mm – and it only makes sense that the larger the engine, the more power you’ll get. The cylinders look nearly identical to stock and usually include everything you’ll need, such as:

  • Piston
  • Cylinder
  • Piston rings
  • Wristpin
  • Circlips
  • Top end gaskets

These kits are made for easy installation and include all the parts you will need to completely rebuild your top end. If you’re up to the task of doing the mechanics, we’ve got a part one and part two instructional video series to show you how to replace the top end on your dirt bike. Make sure you have all the tools you’ll need as well as a service manual and we’ll do our best to guide you through the installation.

Leave your competition in the dust or just impress your buddies with your new-found power and performance when you upgrade your top end with a big bore cylinder kit by Cylinder Works from Rocky Mountain ATV/MC today!

Latest Dirt Bike 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

    MARTIN in CA

    The vertex piston oil ring was pretty cheesy

    Not to sure how long this thing will last . Over all every thing was allright but the oil ring was pretty cheap . You would think they would give a better oil ring thats the only thing i could see going wrong .the stock pistons oil ring was 3 times stronger. Will let u know how it holds up thanks

    Read All Reviews
  • Yamaha GYTR Ported Cylinder Head Assembly

    Yamaha GYTR Ported Cylinder Head Assembly

    James in TX

    GYTR Head

    Expensive engine mod but if you are serious about powering up your YZ grab this and get to the front. Need to use VP u4.4 but you should already be using that if your racing at all . Be sure to set the new mapping to the ECU !

    Read All Reviews
  • Dubach Racing Engine Relocation Kit

    Dubach Racing Engine Relocation Kit

    cody in MO


    Put this on my bike along with the Dr. D radiator lowering kit and the two together made my bike handling a lot better than it ever did before. Recommend both kits for anyone with a 10-13 yz450

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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.

    Read All Reviews
  • 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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