How to Cut Your Air Box for FMX

As the technology in motorcycles continues to progress, so does the rider's experience. Freestyle motocross, or FMX, is a branch of motocross where riders perform daredevil tricks instead of competing for speed. Riders customize their bikes to allow for tricks, such as seat grabs. One such modification includes cutting the factory airbox from underneath the seat, allowing riders to grab onto the bike with this open handle-like area. The airbox's function is to prevent irregular amounts of dirt and debris from reaching the air filter, so frequent maintenance is needed after this customization.

Things You'll Need

  • Electric knife
  • Belt sander
  • Angle grinder
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Instructions

    • 1

      Remove the seat of your off-road motorcycle to access all sides of the factory airbox. Simply pull the rear of your bike's seat up and off of the frame. If you wish to shave off any unnecessary foam from your seat, do so with an electric knife. Polish this piece with a belt grinder to create a slim seat for your freestyle bike.

    • 2

      Cut along each side of the factory airbox. Create an oval-like opening on either side of your motorcycle, just underneath the seat. This creates a grip for the rider's hands, necessary for grab tricks.

    • 3

      Polish the cut edges of the airbox, ensuring that this section of the motorcycle features smooth lines for grabbing. A missed or uncomfortable seat grab at extreme heights may cause serious injury. Cautiously move the belt sander along the cut airbox edges until finished.

    • 4

      Wrap the upper edges of the cut airbox with griptape, further improving the rider's ability to hold onto this section. Griptape is commonly used for the top surfaces of skateboards and can be found at any skateboard shop.

    • 5

      Place the seat of your bike back onto the frame. Snap it into place to secure. Test ride your newly modified motorcycle to check the effectiveness of your cutting.