Step 1 Take old pump off. (This may be more difficult than it sounds.)
Note type of shaft, (Straight or tapered) and size of shaft. (3/4", 1", 24mm, etc.) Order correct pump for your application. Make sure engine is capable of 3500 RPM when not under a load.
Step 2 Make sure keyway fits tight in the shaft slot. Spread a bead of 100% Silicone Rubber all the way around the shaft. Pull recoil rope until keyway is at the top.
Step 3 Turn hollow shaft on pump with a wrench or metal ruler so keyway lines up with the keyway on the shaft of the engine.
Step 4 When sliding pump onto shaft make sure with finger that the keyway doesn't slip out of it's slot.
Step 5 If the pump has a set screw to lock down the keyway, make
sure the pump is pushed on all the way then tighten the set
screw with the proper allen wrench. The allen wrench can be
in the set screw before pushing the pump onto the shaft.
Step 6 Tighten 4 bolts with lock washers evenly until they are tight.