Bombardier SeaDoo 2001 factory shop manual, Page 216Get this manual
Section 06 ENGINE MANAGEMENT (DI) Subsection 02 (OVERVIEW)
OPERATING PRINCIPLE
The Orbital Combustion Process (OCP) provides stratified combustion process resulting from the direct injection of finely atomized fuel spray (less than 10 microns)This is achieved by using pneumatically assisted direct injection system, unique combustion chamber geometry and precise control of the combustion process by the MPEM (Multi-Purpose Electronic Module)
AIR INDUCTION
Air for combustion is drawn directly at the base of the engine through two 46 mm throttle bodiesThe air flow is controlled by two throttle platesThe air continues through the reed valves into the crankcaseF12D01A
FUEL DELIVERY SYSTEM BASIC OPERATION
When the piston reaches the correct position, the MPEM opens the fuel injector and fuel is discharged into cavity inside the direct injectorNext, the direct injector opens and the fuel is discharged into the combustion chamber by the compressed air which breaks the fuel up into very fine mist in the processThis airfuel mixture is then ignited by the spark plug