Having water pump leaking problem, I have just checked the radiator and coolant level was fine. Immediately after, radiator cap start to leak. I found that ruber on the cap is starting to destroy even on slightly touch. Replaced with some piece of old inner tube. Bike is 2007 xtr. It shouldn't happened. Thinking about quality of cap, maybe opening valve with inaccurate pressure is rensponsible for failure of mechanical seal?!