If an outboard engine doesn't start, make sure that there is fuel in the tank and that it hasn't been there for longer than a month. Replace the fuel if it is too old. The engine might not start because the kill switch is engaged; in this case, it needs to be disengaged. Make sure that the kill switch clip is in its place, and try moving it back and forth several times.
The motorcycle can start only if it is set to neutral, so make sure that the engine lever is not in gear. If the motorcycle has an electric motor, charge the battery completely, and make sure that there are no signs of damage, corrosion or loose wires on the battery. The engine might not start because of a problem with spark plugs or ignition system, so use a spark plug tester to detect these problems. Install new spark plugs in place, or contact a technician to replace the ignition system.
If an outboard motor is overheating, shut off the engine, and see if something is in the way of the water flow. Remove the object, let the engine cool down, and start it again. If that doesn't help, check that the water pump impeller is in good condition, and install a new one if it is broken.