CHANGING HONDA VALVE SPRINGS

This is good if you're not familiar with engine maintenance, and haven't done it before. The good news is it's an easy procedure that can be done at the race track if necessary. We recommend that you change your valve springs every four races for the GX-120 and every six to eight races for the GX-160.

1) Remove the 4 bolts securing the valve cover, and lift off the cover. Take care not to damage the gasket, as it may be reusable, though it's preferable to always use a new one. 

2) Next, verify that the piston is at Top Dead Center (TDC). To do this, you need to remove the spark plug and rotate the crankshaft in a clockwise direction until the piston is at the top of it's stroke, and that both rocker arms are not moving. The rocker arms should also be loose, indicating that both valves are closed. 

3) Do not remove the rocker arms at this point, as critical valve timing may be lost. 

4) At this point the valves will be closed, and you can now gently push down with your thumbs on the rocker arm and spring, and rotate the rocker arm away from the spring and push rod.

5) Next, push down and slide the upper retainer out of it's notch, releasing the spring. (On the exhaust valve, the valve rotator cap must first be removed). The valve will drop into the engine slightly, but it will not disappear if you have followed the above procedure to obtain TDC. 

6) Lift the spring off, and replace with the new spring, pushing firmly down until you are able to slide the notch into position. This requires full compression of the spring by pressing down with both thumbs, but is easily possible without the use of a compression tool. ( Remember to replace the exhaust valve rotator cap). 

7) Repeat for the second spring. 

8) Replace the gasket and valve cover and torque the bolts to 100 inch pounds.