Check to see that there is sufficient gas in the tank if the scooter engine will not start. Drain the tank and refill with fresh gas if the fuel is older than 60 days. Fuel can become contaminated if it sits for an extended period of time and cause problems with ignition. Old, contaminated fuel will have a stale, varnish-like odor. If the small holes, or jets, in the carburetor have become gummed up, you may have to soak the carburetor in carburetor cleaner.
Ensure that the choke is set correctly if the engine has difficulty in starting. Pull off the air cleaner and look inside the carburetor to see if the choke lever is open or closed. Verify that the kill switch is set to the "On" position and the ignition is turned on. The kill switch is near the right grip.
Check to see if the engine has flooded. Remove the spark plug with the spark plug wrench. If it is wet, then the engine is flooded. Crank the engine while the spark plug is removed. This will help to evaporate the gas. Verify that the plug is sparking correctly. Hold the end of the plug against the cylinder head and crank the engine. If you notice a strong, blue spark across the gap, then the plug is probably not the problem. Replace the spark plug and try starting the engine.
Ensure that the battery has an adequate charge if the scooter does not turn over when you crank the ignition. If the battery has a charge, check to see if the fuse has blown. Replace the fuse with another of the same rating, if necessary.
Check to see that fuel is reaching the carburetor if the engine cranks but will not start. Remove the thin rubber hose from the carburetor and crank the engine. If fuel does not flow out, the fuel valve may be defective. Replace the fuel valve. Use caution when cranking the engine with the hose disconnected from the engine. Do not attempt this when the engine is still hot.
Check that there is sufficient compression in the cylinder. Remove the spark plug and screw in the compression tester. Crank the engine and check the PSI reading. The reading should be 150 PSI, or more. If the reading is lower than 100 PSI, the engine problem may be more serious. Have a qualified mechanic investigate further for you.
