I know this gets beat to death but I am totally lost.
I have a 1988 KDX 200 (aircooled), My friend has a 2000 YZ 125. What oil and mix ratio would be best suited for both bikes? We hope we can share 1 gas can for both bikes. I know we need something that won't gum up the powervalve but will the same oil work in air and watercooled bikes?
Pick a good oil and run 32:1. That's good for any bike. If there are problems with gumming up, spooging, or fouling plugs then jetting will need to be adjusted.