I have two Iridum plugs lying on the shelf in my garage. They are 16mm. The Iridium plugs did wonder on my old 650GS so I thought why not give them a try on the 800...
After spending an hour on dismantling the plastic panels, battery and air intake I discovered that the plugs were so deep down so any traditional spark plug key (or the one from the toolset to the 650) would not work. You would need a really tall one. Defenitely not something I would like to do by the river....
/Lars