I usually don't give tips because I have to do it for a living all day but, this one needs to be told. On newer 250/300 EXC's the crankcase vents through the powervalve cover to a tube plugged into the frame. The case does not vent into the frame but rather through fitting itself. Here is the problem...the vent tube faces up and when you wash your bike, water runs down the tube and leaves moisture inside the powervalve cover. The moisture rusts the boost port tumbler and the powervalve sticks and will not open. If you use an oil that leaves the valves covered in oil it may not be a problem but, if you use an oil that leaves the powervalve dry and clean (like I do ), they will rust. Route the vent line so it faces down to cure the problem.
you are welcome
F
you are welcome
F
