I pressume Darrsi suggested the rad flush to get rid of any blockages which may cause extra pressure in the system and therefore cause things to leak but other than that I'm not sure how a rad flush would help with the problem you mentioned. Properly cleaning out the system with a good rad flush once in a while ain't a bad idea though. Tightening the clip will defiantely help if it was a bit loose though. 
Chris
When the waterways get scaled up over time the coolant can't travel around properly, then what happens is the fluid gets directed towards the expansion tank and literally boils, i've watched it happen before, then when there's too much coolant in the expansion tank it will just boil like a kettle, rise and dump it out of the overflow pipe.
When you switch the engine off it will cool down and get sucked back into the system.
So if you don't actually know this is going on then the first sign would be a lower or even empty expansion tank.
If everything is normal and air tight then when everything settles down your expansion tank level should more or less stay at the same level, with just the odd top up every now and then, but very minimal.
My old bike used to have a temperature gauge on it, and you could tell if the bike was well or not by even the slightest change, it's something i miss on the Fazer as it was a handy tool to have!
Unless it's a stonking hot day(
), then the fan kicking in is a good warning sign there could be an issue.
That's why i suggested keeping an eye on it, but obviously all jubilee clips need to be done up properly in the first place, that's a no brainer!
