[gasser]

Don't get hung up on what the factory recommends for fuel/oil mix ratios - they don't know which oil you're using. They do know however that most dino oils are not made to work well beyond a ratio of 40/1 and most synthetic oils aren't made to work well at ratios above 50/1 so they probably jet the carbs for a 40/1 ratio. Yamalube 2T is a great oil mixed at 36/1 but do not run it at 50/1. Amsoil Dominator is a great oil mixed at 50/1 but do not run it at 80/1. Always mix any oil you use at the ratio recommended by the oil manufacturer. You can decrease the ratio (more oil to gas) with no ill effects and you will pick up more power because the rings will seal better. That's why a lot of racers will use 36/1, 32/1 or lower.
Now to help you out - If you want to squeeze every bit of power out of your 300 then mix a good dino oil or synthetic mix at 32 or 36 to 1 (kawasaki racing, Yamalube 2T, and Klotz are some that I like). Be sure to rejet your carb if you use the lower oil mix ratios because adding more oil will result in less gas being mixed with the air in your carb therefore leaning it out and making the bike run hotter - maybe too hot. If you want to run 40 or 50 to 1 any of the better synthetic oils should give you just as good wear protection as those same oils would give your engine when mixed at 32/1 but not as much power. The advantage to running less oil is less smoke, less pollution, a cleaner engine, and a cleaner silencer. Personally after trying all the good synthetics I settled on Amsoil Saber(100/1). It is noticeably cleaner than the others and offers full wear protection up to 80/1 under racing conditions and 100/1 under normal conditions. I run 64/1 which is 2 ounces per U.S. gallon. My reasons for switching from 43/1 to 64/1 was to save money, reduce cleanings of the power valve and silencer, and smoke less than the other 2 strokes. Changing my mix ratio that much did cause jetting to be a little rich.