I have completed the break in on my rebuilt 1997 GTX and am now going to straight gas in the tank and relying on the oil injection system to function properly to keep the engine alive. I tested it using the reverse drill when the engine was apart and I've tested it using the 'hold it open at idle with engine running' technique and it seems to be working. My question is, how do these pumps work? When I hold the cam wide open I can see the oil 'pulsing' in the lines ever few seconds, kjnd of like a mechanical heartbeat. At idle it barely moves. So, am I right in thinking that the pump just spins away and gradually builds pressure up in the lines until it reaches a 'tipping point' at which time it overcomes a check valve in the little output lines? I did put a vacuum tester on the discharge nipples when I had it apart and they do hold at low vacuum pressure and then release as pressure increases. So the faster the pump spins the faster pressure builds up and the more often the nipples will discharge oil. And some clever Rotax engineer has designed the system to deliver the appropriate oil for the rpm the motor is at, provided you have it lined up correctly.
Have I got this about right? I'm just trying to get more familiar with how this engine works.
Have I got this about right? I'm just trying to get more familiar with how this engine works.