I have owned a 99 yz400 for a few months now. I accidentally dropped it in a mud hole while riding. I made the mistake of running to get it to my truck to take it home. It ran perfect for several weeks, then... I noticed a rattling in the top end and it didn't want to stay at idle. I discovered there was water in the oil, so i flushed it several times with diesel fuel and oil. The majority of the water is gone, but the problem still exist. Any advice?