I'm just in the middle of a medium service of which the plugs is a part....pain...
Mine didn't come with a plug spanner so used an old thin metal one as the cylinder head has a step halfway down that stops you using a normal socket set one. It wasn't quite long enough either so i had to hammer a 1/2" to 3/8" socket convertor and undid that way..
i also took the airbox and carbs off..
Yes be very careful removing the plugs and inserting new ones, use a peice of hose to put new ones in you should be able to get at least five complete turns by hand otherwise its not in correctly...sorry don't mean to tell you how to succk eggs n all that.