From what you saying, sounds like the rotary valve seals on the crank are bad. The seals keep the oil from entering the combustion chamber, allowing the oil from the injector to lube the rotary shaft of the rotary valve. If the seals go bad than the oil seeps into the crank under the combustion chambers, and enter the cylinders as you reported. To repair this problem the engine must be pulled out, and the cases split to replace the seals. This is not a easy repair and requires mechanical ability and the correct tools to perform this repair. If you want to perform this repair yourself you might want to become a "premium member" so you have access to the repair manual sections on the seadoo forum. The manuals have the the proper procedure to perform this repair. The seadoo forum has authentic seadoo manuals that will get you through the repair. If you get in a jam we are here to help you get back on track. If you decide you want to tackle this yourself and want the manual click on the "seadoo Manuals" link at the top of the page for details. If you have any other questions give us a shout.
Karl