The easiest way to change this type of bulb is to remove the air filter housing. Start by removing the air filter on this common air filter housing. The highlighted area shows the 3 screws to remove. Once removed, pull the housing straight out.

Identify which type of primer bulb is used as there is one with a vent hole and one without. This type of air filter housing uses a bulb with a vent hole in the center. Note that the white clamping ring has beveled ridges and that they face outward at the top. These beveled ridges will lock into the housing.

Use a pliers or similar tool to depress the beveled tabs that hold the clamping ring in place and move the primer bulb outward. Note the position of the tabs in the housing. When reinstalling the new primer bulb, you will have to line the clamping ring taps to align with the squared openings in the housing.

Install the new primer bulb using a �" socket. Align the tabs with the openings in the housing and push inward. It may require a good deal of force to get the tabs to lock in place. If they visibly don�t lock in place, the primer bulb will not be sealed and won�t work properly, or not at all.

On the back side of the housing, remove the old gasket, if necessary. Note the passageway for air under the gasket.

Install a new gasket, if necessary. Note the small hole in the gasket that provides air to the carb to force gas up and out of the tube. With the air filter removed you should see gas squirt up out of the tube in the carb when pressing the primer bulb. Sometimes the air filter housing is warped and two gaskets are used. Do not overtighten the 3 screws when reinstalling the housing. Note on the top left of the picture the plastic nipple that gets reinserted into the breather tube coming out of the engine when you put the housing in place.