i have a kx 125 and i keep fouling out plugs we ran a hotter plug fould out in 30 min when we take it out the part thats in the header is liquidy and pitch black we treid running my fuel mixture 50:1 still doing same thing we get a lot of smoke at the begging and alot of blow buy at the bottom on surtain days it will run fine but when i shut it off it wont start unless i put a new plug in it