I recently got back into riding and bought my first decent bike (had an old ag bike on the farm when i was a kid) 99 YZ400F about 6 months ago and it has been great so far apart from a few minor hick-ups (countershaft seal and water pump seal) but i have done 20 odd hours without checking valves. It died on me on the trail last weekend so i got it home and pulled off the head cover to try and check the valves and found the cam chain has stretched and one of the camshafts has slipped around 4 teeth. I've read through the manual and it doesn't seem to complicated to replace the cam chain but i'm a newbie with little motor knowlege. Is there more damage that I'm not aware of? Am I up for big $$$ ?