undefined I am having trouble diagnosing my problem with my motorcycle. When I start it up it idles fine for about one minute then it idles up to full blast and spits black liquid from the exhaust. I have checked the carburetor and it is fine, the gas is not sticking. It seems like it is sucking crank case oil into the cylinder I don't know if it is because I need a two ring piston or not. I have no clue what is causing this, nor how to fix it, any help would be greatly appreciated.