need help fast look here

[wantablaster]

I was riding my 300ex and everytime I would shut it off it would only start back up when it felt like it I had to catch it in gear and it would usually start then. Im pretty sure its my spark plug but I need to know what size socket to use to get the plug out im thinking I need a 14mm but the problem is I have everyother size socket but cant find the 14mm.

Is this problem the spark plug and what size socket do I need?

[2muchquad]

i forget the size right off hand but i think its bigger than a 14mm.at least the ngk plugs are bigger for it

[Sjorge450R]

18mm.