I bought in o7 wr450f in 2007. The engine has no more than 30 minutes on it. Never wridden, just turned over from time to time. As im now in a position to wride the WR I've set about servicing it. Whilst servicing the bike, it was noted that coolant was leaking from the weep hole. The parts where ordered and today I cracked open the crankcase cover to replace the defective seals. The effin impeller shaft is worn/grooved. THIRTY MINUTES OF USE and the shaft is toast. What a piss take. The impeller bearing is 'gritty' as well. I've cleaned the bearing but its still not stictionless. *** did I buy this bike? To be reliable... So why has the impeller shaft failed? *** is wrong with the workshop manual. It gives BS advice like "remove the header" if removing the rhs crankcase cover. Equally "remove the seat and left side rear panel to drain coolant" FFS its a sodding press clip that holds the coolant pipe on. 10 seconds work to drop the pipe. Yet the manual states to remove bodywork. Equally why in gods name did yamaha not sink an allen fitment in the impeller shaft so you can hold the shaft whilst removing the impeller. Imo bad design. Then there is the Ti valves. WHY do the r6/r1 ti valved bikes get away with thousands of miles of use without need to adjust the valves? Not happy. Next time I buy a bike it wont be blue.