Why do you want to disconnect the vital oil supply? If you are experiencing too much blue smoke or plugs oiling you can adjust the amount of oil fed to the engine via the secondary oil pump cable,the one that splits off from the throttle to the carb.
If you disconnect the cable it also stops the oil pump sending oil to inlet, winding out adjuster increases oil screwing in reduces.
As for ratio? trial and error as No knowledge/specification is available for Oil injected engines, poss 25:1 to start but don't blame me if you seize?
Quality synthetic oil is always a must, did you know you can also purchase smokeless two stroke oil?
Please remember the Fixya button if my efforts are respected?
just use about 3 to 4 ounces of 2 cycle oil per gallon and you should be fine. a little extra lubrication wont hurt it
You can pull the oil tube off the carb for a couple seconds while its running to see if it drips oil. I'd run a synthetic 2 stroke oil, lubes better and burns cleaner.
My echo uses 50-1 ration. Home Depot sells the small containers for Echo Leaf Blowers that you mix with one gallon of gas.