When the exhaust valve closes, the inertia of the gas causes a vacuum behind the valve. Because of this, the air coming from the air filter passes through the air intake valve and arrives behind the exhaust valve to oxidize the unburned hydrocarbons. When the pressure behind the exhaust valve is greater than the atmospheric pressure, the air intake valve closes and prevents backfiring.
The air injection system is composed of:
- Two air intake valves.
- Four air injectors (the injectors are placed in each exhaust outlet behind the valve).
- Two pipes connecting the air filter to the air intake valves.
- Pipes connecting an air intake valve to cylinders 1 and 4 and the other valve to cylinders 2 and 3.
Check one way valves in the same manner as done in checking one way valves with air pump system.