I know this is an old thread, but this topic is near and dear to me as recently, the ALT50 trailbuddy I gave to my nephew last year for Christmas was ruined because I decided to leave the stock oil injector hooked up even though I knew better. Like Jack said, they work until they don't. When they go out, it's an expensive fix. Usually so much so that the bike isn't worth fixing and basically becomes a parts bike.

In the case of my nephew, the oil hose either ripped or came off on one of the ends (not sure which end since I didn't see it). He drove it all around their house watering the yard with Champion 2 stroke oil. When the engine finally ran dry, it ruined the lower end.

That's just one way these things can go out. My '87 LT80 has WAY too much money in it to trust it to a 27 year old oiling system, so I ditched it when I built my motor. (My motor, coincidentally, originally had to be rebuilt because it quit oiling properly. The lower rod bearing went out and so I decided to put some money in it building it up when I did that.) I was hoping to get away with leaving the factory oiler on the little ALT50 even though I knew better.

I'm 0 for 2 so far in the long run on trusting the factory oiler.

So despite what people say, removing the oil injector and running pre-mix is the only truly safe way to go. If you've got a cheap bike and it's not worth much, and you don't want to mess with pre-mix, I guess you can trust it until it goes out. But if you build a really nice little 80 (or 50) and have some blood sweat and tears (and money) invested, you'd be an idiot to trust the factory oiler.

Just my .02.