OK, this has happened twice now for no particular reason. First time was on a fairly warm day, around 32 or so, but never got stuck in hot traffic and the coolant temp never got above 100. Stopped, shut her off, and the coolant started running out the little hole in the cap on the overflow tank. At that time, it was full to the upper line. It wasn't a drastic amount but it still spewed all over the ground. Embarrasing more than anything. That was 2 months ago. Today it was about 23 or 24, again no traffic at all and the coolant temp probably never got above 95 or so. Got home, shut her off, and she started to spew again. Note, I never added any more water from the last time this happened and there's been plenty of warm hard ridden days in between with no incidents. What's up???
Radiator fan not working? Check the wiring to the fan,there have been a few cases where the wires are routed too close to the fan blades and have been chafed. If the water is not boiling up you may have some sort of airlock in the coolant system.Make sure none of the breather pipes or vent holes are blocked.
Similar thing happened to me. It turned out to be a duff radiator cap not allowing the system to pressurise, as soon as the coolant got hot and expanded it just went around the seal, into the header tank and then all over the floor.
Everything seems to be working fine. Fans don't even come on until 100+ or so. Last time I noticed both were working just fine and I'll check the hoses but pretty sure they are good to go. As I stated, I have seen much hotter temps on much hotter days without this happening. Guess that makes it seem even stranger.
I don't know ducatis that well but one thing no one has said and I hope it is not but it just might be is a head or headgaskit just starting to go, have you checked the leave in your Radiator not your header tank, you might have a leek and don't know as no some bikes it needs a -air presser to pull the coolant thought from the header tank, it's hard to explane, but the bottem line is check the rad,