do you have the tool kit that came with the quad ?
there should be a socket in the kit that will take the plug out , granted its not much fun to do with the engine hot but it does do what its designed to do, the rubber thing in the socket is important to have in it , spark plug sockets have it to hold on to the plug.
on the right side of the head you will find a small hole , use air to blow out any dirt or water that may be next to the plug before you take out the plug.
the gas tank is easy to get off and if you dont have the tool to do it taking off the tank is no more that gas lines 2 small bolts and them 6 snap in things
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