• Too much gas in the intake - hold the throttle to the floor and crank the starter for 10 seconds, wait 30 seconds and do it again. This might clear the excess gas.
• Of course bad spark plugs, wires and ignition points can cause hard starting. Be sure these items are in good condition.
• Do you smell gas after turning off the engine? Look down the carburetor after turning off a hot engine. Do you see gas dribbling from the venturi. Gas may be siphoning from the main discharge due to the check ball not seating. Tapping on the ball gently will form a better seat.