i use the box spanner that came with the srx6, it's long enough to reach the plug (with a rubber ring inside to grip the plug) but short enough to fiddle past the frame.....but in all honesty...i usually have the tank off and check the tappets and stuff like that when i'm doing the plug...and i'm always concious of the fact that a lot of crud gathers round the plug and is just waiting to fall throught the hole when the plug comes out, so i try and blow that out first....not easy without removing the tank.