Hey, even at 80:1 on Motul 800 my trials bike will spooge up the pipe from all the putting around we do.
No matter what the mix, you have to get the thing hot enough to burn out the excess that accumulates. I run the Monty WFO in 5th dragging the brakes 3 or 4 100 yard passes. That gets it hot enough to burn it out.
Some WFO drag races in the open with your buds is a good way to keep your woods bike cleaned out if your normal riding does not include much sustained high rpm under load. Lower gears and high RPMs won't do it - the wind resistance at higher speeds is what creates the load and builds the heat.
Oil amount differs based on the use of the motor and quality of the oil. Some guys run the 100:1 amsoil. I have a friend that runs it in his Rotax 503, a air cooled twin used for ultra-light aircraft. It gets lots of sustained load and he's had no measureable wear at 100 hours of run time. Amazing.
On the other end of the spectrum, dyno tests on shifter cart motors, the highest sustained output load you'll put on a 125 motor, show that the engine will keep making more HP as you add oil right up to 16:1, then power starts to go back down.
Netting it out, for your average woods application you are in pretty good shape at around 50:1 with a decent synthetic or semi-synthetic motorcycle-specific premix oil. Bel Ray, Yamalube 2R, Motul 600 or 800, Silkolene, Golden Spectro, etc. will do the trick.