04 yz 250 last season I really sunk the bike in a deep mudhole, cleaned up the bike got it running but there was oil spraying from the silencer; so I thought it would be a good time to tear down the top end and have a look. Just finished doing the top end, repacked the silencer yet I stil have oil misting from the silence. I am concerend that this may be a blown crank seal. Any thoughts or confirmations would be helpful. How difficult is it to replace a crank seal? does the motor have to be removed from the bike, I youtubed this but couldn't find anything.