Recently, a fellow blogger described how his 2012 WR450 got a bad case of "sand in motor". It gets in through an unfiltered air passage in the airbox, and routes to the crankcase.. (Open the air filter door, look at the bottom edge of the airbox. There it is). Here's my fix: Add an "vent" air filter to the hose end that routes to the motor. I chose a K&N 62-1010. I'm about $25.00 lighter, but I wont be tearing down a motor, splitting the cases to get the sand out of it. Cheap Insurance. Moderator, I request this be made a "sticky". No one should have to suffer through an engine teardown because of routing unfiltered air to the crankcase.