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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

    Josh in DE

    Best bang for your buck

    Night and day difference installed on my drz400sm paired with stage 2 hot cams

    Read All Reviews
  • KTM Big Bore Kit

    KTM Big Bore Kit

    Horacio in AZ

    Perfect bolt on!

    I had the shop install it to perfect the jetting with it too. works great. bought one a while ago from a shop and ended up selling the bike. Going to buy one again for my newer XC.

    Read All Reviews
  • Yamaha GYTR Ported Cylinder Head Assembly

    Yamaha GYTR Ported Cylinder Head Assembly

    David in ND

    GYTR Ported Cylinder

    Although this, and everything else that is GYTR, is ridiculously expensive, it fits well, and seems to work well so far. Straight bolt on, with everything included. Only one ride so far, so can't really say if it's durable, but seems to give a little more snort, if only between my ears.

    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

    Read All Reviews
  • 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
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