First, I know, its a SunL Brand 50cc 4 wheeler so I do not expect much. I am doing some general maint. on it since I purchased it used and the fluid that came out of the engine/transmission does not smell nor look like regular crank case oil. This is an older (couple of years) 2 stroke model 50 CC quad, I cannot find an oil fill on the main engine, the only one I found was on the top of the transmission towards the back of the bike. My assumption here is that since its a 2 stroke, there is no engine oil, just the transmission fluid. Does anyone know what fluid is used in these transmissions?

-d

I would just stick ATF in there and it should be fine. Not sure what kind of set up you have but both my little 2 strokes with auto clutches do fine with regular ATF or motor oil, always heard you should avoid oil with the energy conserving symbol.

There is no oil in the engine, other than the pre mix or injector oil if so equipped.

those have a wet clutch system, just like your 2 stroke dirt bike. i use castrol 20w50 in my bikes and my sunl 4wheeler.
on the back of the oil container there is a round 'certificate' about the size of a dime. on the bottom half of the certificate if it says 'energy conserving', the do not use it. that oil will have teflon or some additive to allow slippage, something you dont want on your clutches.
just my 2 cents.