It's not really that complex. 2t oil is flamable but not as much as gasoline, and even less than gas/air mixed into a vapor (air/fuel mix).
The oil doesn't really burn when injected in the correct amount. It needs to stay an oil to lubricate so the lower flash point makes it sort of evaporate off inside the pipe. That's why 2t bikes are always dirty/greasy.
The injector meters the amount for throttle position, and that is a VERY crude approx. of rpm. Too little oil, and cylinders/crank bearings suffer. Too much oil, and combustion temps fall.
Kymco does a good job of regulating the oil, and they use a decent/reliable oil pump. When it is adjusted correctly, and you are using a good quality injector oil... there are no real issues.
T%he only reason I removed my pump, and run Pre-mix is, I run high load cylinder kits. Let's say I am running 11k rpm at 900* f exhaust temp... I let off the throttle... The bike is still spinning wicked high rpm and the temp will rise. This is due to "soaking". The parts are hot, and the cooler air/fuel mix has been cut off. When I pre-mix there is a constant amount of oil, and most of that oil will remain in the crankcase simply because it is denser than the air/fuel. That iol can now be sucked up into the cylinder, and cool things down.
Your injector only gives what is needed according to the throttle position. WOT you get near 50:1 ratio. idle or closed position you get near 100:1. Even tho your throttle is closed you are still getting 100:1 (thru the pump) but there is no excess oil to cool the cylinder.
For an example... You will NEVER find any Pro Super Bike running an injected engine. They all run pre-mix.
Outboards get away w/ it simply because they are run at or near WOT all the time. They rarely throttle down.
Now the confusing part... Jetting for pre-mix requires you to use a larger jet (compared to injected).
The reason is oil takes up space. The jet needs to allow for the right amount of gas, and now you also need room in that jet for the oil.
See... It's really quite simple.
Don't worry about asking these things
. It's how we all learn.