Here is my nightmare of the week. I have a new 2001 WR426 that I changed to YZ timing before the first ride. The bike has a total of 89miles & 4 rides on it. On the 3rd ride the Stator & flywheel detonated. Warranteed through Yamaha no problem....4th ride the new stator & Flywheel detonated again. After approx 5weeks, taken the whole motor apart, split the cases etc.... Here is the problem: When attempting to convert to YZ timing:Be very careful when attempting to pull the top of the Cam Cap off of the camshaft. There is a halfring that keeps the cam bearing in place. Be very careful lifting the cam cap off. The halfring will and can fall into the motor as in my case. The bike ran fine the 1st & 2nd ride. The ring needed time to work through the passages. After a lot of time & $870.00 to repair all damage, I will be getting the bike back. But be aware that Yamaha has posted to the dealers a notice that any warranty claim on a WR that has been converted to YZ timing will not be warranteed. Apparently, a lot of claims are coming in now & guess what? The halfrings are on back order due to the large number of problems due to this modification.