2002 yamaha bear tracker 250
 

my bear tracker leaks gas out of the overflow hose after running. It leaks even with the gas shut off, it will leak a whole tank of gas out. I also would like to know how to adjust the idle speed. ATV will not idle. Hard to start, but runs well.

Looks like you have 2 problems: 1 - Your gas shutoff doesn't work 2 - Your floats in the carb are set too high, the float needle/seat are worn out, or the float needle/seat have trash stuck in it. You'll have to pull the bowl off the bottom of the carb to check it out.