How to Change the Sleeve on a CR250

The Honda CR250 is an off-road, two-stroke, "motocross" style dirt bike. As its name suggests, the CR250 has an engine displacement of 250cc and is notable for its aluminum frame, liquid cooling system, large single rear shock absorber and telescoping inverted front suspension forks. The CR250, like all dirt bikes, requires regular inspection and maintenance for things like cracked cylinder sleeves, which can severely inhibit performance. Replacing the cylinder sleeve on a CR250 is a lengthy chore requiring the removal of several other pieces.

Things You'll Need

  • Oil pan
  • Adjustable wrench
  • Screwdriver
  • Rubber-handled tongs
  • Oven
  • Freezer
  • Oven mitts
  • Replacement sleeve
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Instructions

    • 1

      Place your replacement sleeve in your freezer overnight to give it time to get cold.

    • 2

      Preheat your oven to a low temperature -- no more than 150 degrees F.

    • 3

      Unscrew the cap to the coolant reservoir, and drain the radiator fluid into your oil pan.

    • 4

      Unscrew the two nuts holding the seat in place and remove it from the bike.

    • 5

      Locate the fuel tank. Flip the valve switch directly below it to close off the fuel hose and tank. Disconnect the fuel hose from the tank. Unscrew the mounting bolt holding the fuel tank in place, and remove it from the bike.

    • 6

      Loosen the two nuts holding the large rubber expansion chamber in place next to the fuel tank. Remove the expansion chamber from the bike.

    • 7

      Loosen the screws holding the carburetor and its connecting tube in place. Move the carburetor out of the way enough to allow you access to the engine cylinders.

    • 8

      Loosen the nuts holding the relevant cylinder head and gasket in place and remove them.

    • 9

      Loosen the nuts holding the cylinder in place and remove it from the bike.

    • 10

      Open the clips holding the piston in the cylinder and remove it, setting it aside for later.

    • 11

      Place the cylinder, which should still be in its sleeve, into your oven. Allow it to heat for approximately 10 minutes. Remove it from the oven using the tongs. When handling the cylinder, it should slip free of its sleeve.

    • 12

      Remove your replacement cylinder from the freezer, and slip it around the heated cylinder. Align all of the connecting holes together as closely as you can. The cooling metal of the cylinder and the heating metal of the sleeve will lock themselves firmly into place.

    • 13

      Reassemble the piston, the cylinder, the head, the gasket, the carburetor and its connecting tube, the expansion chamber, the fuel tank, the fuel line, and the seat of the bike in the reverse order that you disassembled them.

    • 14

      Replace the coolant in the radiator to complete your reassembly of the CR250.