The small hose on the thermostat housing, does it go to the expansion tank pipe. I.E. make up a T piece to install? All other pipework seems OK so far. This pipe was only discovered hanging down side of engine and leeks out when engine gets warm, but where's it go to?

If you look down the posts a bit you will find one titled 'ZX9R C2 plumbing'. In it is a link to Ben Marriot's plumbing diagram, if you follow this then everything will be fine.

Steve