A mates son had a conrod failure on a 03 Huaky TC250 fitted with a 300cc big bore kit on the weekend he told me he was giving it a good rev, managed to punch 2 holes in the crankcase, break the bore liner and even broke the caps that hold the camshaft in the head, the valves lifted the cam as they were driven into the head by the piston as the little end broke on the conrod, my mate is a mechanic and has rebuilt this motor few times over the years, lack a lubrication under the piston was the cause of the failure, I have had a 99 WR400F since new, it was raced for a couple of years then trail ridden since has about 13000km on it, all I have done to it is change the oil, cleaned change the filters brake pads, coolant and had the valves check they have never needed adjustment, is has been registered the last 17yrs and has been very reliable, its worth maybe a couple of grand, its to be retired as I have an a 2016 WR450F on order.