NGK spark plug. The spark plug ignites the fuel and air mixture in the cylinder to power the engine. If the spark plug is burnt, fouled or damaged the engine may not start or may run rough.
Honda fuel tank joint. See recommended related for the o-ring seal needed to complete installation.
Honda flywheel key. The flywheel key aligns the flywheel in the correct position on the crankshaft. If the engine stops suddenly due to hitting a hard object, the flywheel key shears in half to prevent damage to the engine. If the flywheel key is broken, the engine won't start.