Things You'll Need
Metric socket and ratchet
Timing light
Screwdriver
Periodic maintenance of your Honda CR125 dirt bike includes setting the timing for maximum engine performance. The correct setting ensures that the spark plug generates spark in conjunction with the combustion stroke of the piston. The timing unit is located behind the timing cover on the right side of the engine crankcase. You set the timing by aligning a mark on a flywheel with an indicator-pointer at the top of the timing plate. Setting the timing on a CR125 requires a few hand tools and a timing light.
Step 1
Park the motorcycle on its kickstand. Loosen and remove the timing cover bolts with a metric socket and ratchet. Save the bolts and pull the cover off by hand. Carefully remove the rubber gasket from the face of the timing housing by hand. Save the gasket.
Step 2
Clip the red wire lead from a timing light onto the spark plug wire. Clip the black wire lead onto the black ignition coil wire. Start the motorcycle and allow the engine to idle at normal speed.
Step 3
Aim the timing light at the indicator-pointer at the top of the timing plate. You will notice that each strobe of the light illuminates the timing mark on the flywheel. The timing is set when the mark is directly in line with the indicator each time the light strobes.
Step 4
Loosen the small screws on the face of the timing plate one-half turn with a flat-tip screwdriver. Insert the tip of the screwdriver into the adjustment notch at the base of the timing plate.
Step 5
Aim the timing light at the indicator. Twist the handle of the screwdriver to the right or left, as necessary, until the timing mark is directly in line with the indicator. Tighten the screws securely on the face of the timing plate.
Step 6
Turn off the engine. Disconnect the timing light leads from the spark plug wire and the coil wire. Press the saved rubber gasket into the recess on the face of the timing housing by hand. Reattach the timing cover and tighten the bolts with the socket and ratchet.
Tip
Refer to the service manual or consult a mechanic for additional information on setting the timing when using a high-octane fuel mixture or racing ignition components.