Lift your cooled Harley on a hydraulic center lift, disconnect the negative cable for the battery and then remove the air cleaner by unscrewing the air cleaner cover the a large hex key from your set. The size of hex key required will vary dependent on your model of Harley. Once the cover has been removed, take off the cleaner cover. Use your screwdriver to loosen the screws of the air cleaner filter and place off to the side. Then use a small hex key to disconnect the carburetor's backplate. Remove the spark plugs.
Use your flat tip screwdriver to compress the spring cap retainer and pry it free from the pushrod cover. Then slide the cover down to gain access to the pushrod. Remove the O-rings by pulling them out with your fingers.
Roll the rear wheel of your Harley until the rear exhaust valves are opened, and then pull the pushrods out of the engine compartment.
Adjust the new pushrods by hand for zero clearance. Having zero clearance means that there is zero play, or that there is no depression of the plunger or lifter. There should be zero tension on the pushrod while adjusting. Hold the pushrod with your hand and rotate so that it is in the middle of the lifter. Roll your rear wheel to ensure that the valves are closed. Replace the O-rings. Reinstall the spring cap retainers of the pushrods and the pushrod covers.
Reinstall the spark plugs. Use your small hex key to reinstall the carburetor backplate. Reinstall the air cleaner. Reconnect the negative battery cable. Lower the Harley to the ground.