DIAGNOSIS Cold weather starting difficulty. The engine requires a richer fuel mixture and solid spark. The most common issue is a weak spark from a fouled spark plug.
FIX Remove and inspect the spark plug. Use a spark plug wrench. The correct plug is an NGK BPR6ES. Check the gap: it must be 0.028-0.031 inches. The electrode should be light tan, not black or wet. Clean it with a wire brush or replace it. Ensure the spark plug wire is firmly attached.
IF THAT DIDN'T WORK The fuel mixture is too lean for the temperature. Use the choke fully. Pull the starter cord slowly 2-3 times with the ignition OFF to prime the cylinder. Then, turn ignition ON and start. Once started, leave the choke partially on for 60-90 seconds before fully opening it.
HEADS UP Never use starting fluid on this engine. It can damage the piston and rings. For reliable cold starts, always use the recommended SAE 10W-30 oil. 20W-50 or thicker oil will make cold starting very difficult.