my 400ex has been making a growling noise out of the clutch side and when you pull the clutch in it goes away i recently replaced the clutches pressure plate bearing because i thought that was the problem but it didn't fix it,i took a ride today and on my way back it made a screech noise then again then next thing i know the motor dies and i drifted to the side of the road,i got pulled back home and washed all the mud of it the i checked the oil which i recently changed and it was full then i checked the gas tank it was full also ,then i checked the spark plug and there were no signs of running lean.i thought the motor locked up but it started right up then i killed it so no other damage was caused, do you think a transmission bearing is bad or the bearing behind the clutch basket or something? has anyone had this problem?i know for sure the clutch and the disks are put an correct and all of the washers went back as they should i found one post on atvconnection the guy had the exact same problem but nobody replied i started the bike up again today and it ran perfect