Six-stroke cycle engine having scavenging stroke

A six-stroke cycle engine including a scavenging stroke, comprising:

• an intake passage including a downstream end connected to a combustion chamber and having no throttle valve therein;
• an exhaust passage including a catalyst and an upstream end connected to the combustion chamber;
• a first valve configured to open and close the intake passage;
• a second valve configured to open and close the exhaust passage;
• and
• a valve gear configured to operate the first valve and the second valve so that an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are executed, in this order, and to operate only the first valve so that a scavenging intake stroke and a scavenging exhaust stroke are executed, in this order, following the exhaust stroke;
• wherein
• the valve gear includes a variable valve mechanism configured to continuously change an opening and closing timing and a lift amount of the first valve;
• and
• the variable valve mechanism is configured to control an intake air volume during the intake stroke.