I heard something today that interested me. I was told by an independent repair shop tech that the YZ cam timing is only half of the difference between the WR and YZ 400 engine.He was under the impression that the YZ has different ignition mapping, and a higher rev limit. Has anybody heard the same,and if so, have you tried the YZ ignition box? I don't know if different spark curves are used,but it does make sense. I rode a bike with YZ timing and personally didn't care for it. I ride mainly heavy woods and prefer the snappy low end. It seems that the YZ was kind of soft down low.Maybe different ignition curve would change this?