I have a '78 puch newport which has the 1.5 HP sticker on it, but I have reason to believe that the previous owner put the 2 HP cylinder on it. My cylinder head does not have a head gasket, just a "sealing groove". I know for a fact that the 2HP version has this. Does anyone know if the 1.5 HP version uses a head gasket or a sealing groove? Thanks, I need to buy the appropriate spark plug but I need to figure out if its 1.5 or 2 HP first.