How to Do a Top End on a Honda CR250

Based on your use of your CR250, you should rebuild the top end after every 40 to 100 hours of use. You will notice a loss in power or a weak idle when your top end needs to be rebuilt. It is a basic job that can be done at home. When replacing your piston, you should always replace your C-clips and wrist pins. Ensure that you purchase your replacement piston from a reputable manufacturer.

Things You'll Need

  • Socket Set
  • Screwdriver
  • Spring puller
  • New piston
  • 2 new C-clips
  • New wrist pin
  • Needle nose pliers
Show More

Instructions

    • 1

      Remove the gas tank by removing the bolts that secure it.

    • 2

      Remove the rear portion of the frame by removing the bolts that secure it.

    • 3

      Drain the coolant from your motorcycle by removing the drain plug at the bottom of the engine.

    • 4

      Use a tusk spring puller to remove the springs that secure the exhaust pipe. Remove the pipe.

    • 5

      Remove the top motor mount head stay by removing the bolts that secure it.

    • 6

      Remove the spark plug by unscrewing it.

    • 7

      Remove the radiator hoses by unscrewing the clamps that secure them.

    • 8

      Remove the engine head by removing the six bolts that secure it.

    • 9

      Remove the head gasket by pulling it out of its socket.

    • 10

      Pull out the two centering dowels.

    • 11

      Remove the power valve cover by removing the bolts that secure it.

    • 12

      Remove the linkage bolt using a socket wrench.

    • 13

      Loosen the cylinder bolts and remove the cylinder.

    • 14

      Pull the C-clip out of the groove in the cylinder using a small flat head screwdriver.

    • 15

      Slide out the wrist pin. The piston is now disconnected from the connecting rod. Remove the old piston

    • 16

      Slide the new piston onto the connecting rod.

    • 17

      Install the new C-clip by pressing it into the groove on the cylinder.

    • 18

      Slide the new wrist pin into its slot.

    • 19

      Slide on the second C-clip using needle nose pliers.

    • 20

      Slide the cylinder back onto the bike and tighten it back into place. Tighten the bolts in a crisscross pattern for even tightening.

    • 21

      Reassemble the rest of your bike in the exact opposite order that you disassembled it.