Yes it will come out without removing the tank with the stock plug wrench or a socket. the easiest way I found to do it is to shut off the gas and stand it up on end on the rear grab bar...makes it high enough so its not at a goofy angle to get in there and do the work. This also makes it easier to start it back in by hand so not to cross-thread it.
2002 Honda 400EX
--FMF Power Core 4
--airbox lid removed, K&N air filter w/outerwear
--42 pilot, 170 main
--Wiseco 11:1 piston
--Hotcams stage 2
--Race-cut front fenders
--Quad Boss nerfs
--B&M Racing Air Scoops from Pro-Fab atv