Whats the correct fuel oil mixture for a 1990 Kawasaki kx-125?

I have a 1993 kx 125 and found that the owners manual says to use premium gas (90 octane or higher) with a 32:1 mixture but i found if I used premium pump fuel with 32:1 it would fowl out the spark plug with oil. I would recommend using a 40:1 mixture with premium gas but if you want to use 32:1 you should probably get some race gas (100 octane). This should run fine. Using the premium gas with a 40:1 mixture will call for more frequent piston/ring/cylinder replacement but it wont be much of a difference.