OIL PUMP Theory's

[FULL-THROTTLE]

Lets talk two stroke oil pump operation,

I have twin 7878's:

1. Is there a method to check the oil pump when it is out of/off the engine?

2. What kind of oil pressure does the pump send out to the intake?

3. We all know you will use considerably more oil if you go to a straight premix, but why? does the engine & oil pump lean out the mix at higher speeds.
Theoretically if you are running at 40:1, with the oil pump you should use the same quantity of oil if you are running a premix in the fuel tank. Slow speeds means less fuel & less oil, higher speeds means more fuel & more oil.

4. How many people have had an oil pump go bad? therefore when should you replace them. I would prefer to change mine before they go bad. I know bad oil pump means, broke down, overheated, siezed, expensive, and really bad day.

I think this thread will help many understand the oil injection system and how to maintain it.

Thanks,

 

[nswillin]

The good ol oil pump question.

Rotax uses a variable rate injection that works off the throttle, more throttle, more oil. When using premix say 40:1 it is giving the engine a 40:1 ratio of oil at all times even when idling, that why premixers will smoke a little more when just idling around.

Not only will you use more oil, but it's a pain to mix up everytime you fill up, and with synthetic oils, IMO they don't mix up as well.

There is a bench test for the oil pump off the Seadoo. You have pull the pump off and leave the lines hooked up. Hook the drill up to the pump shaft and run it counterclockwise. You should see it dripping out of the fittings from the Rotary Valve Cover.

There is another test where you measure each port separately and measure the amount in ml but you have to have someway of reading RPMS at the drill.