I have a 2001 WR426 that I recently timed to the YZ specs. It seemed to run fine for a while. But recently it has started popping when trying to accelerate. If you ride it real nice and slow and not rap it up it runs fine. But when you try to go past about 1/4 throttle it starts missing. It seemed to do it worse up at about 8000 feet than around my house at 5000 feet. And sometimes it doesn't do it at all sometimes it runs fine. I am not sure at this point that it is even jetting related. I was thinking maybe it is a timing problem or something. Any advice would be greatly appreciated!