[kz1000st]

My theory is that the Chinese maintain some fairly tight tolerances in building the engines and it takes awhile for EVERYTHING to break in. Bearings work harden and even the valves loosen up in their guides. I won't get into the ring seating discussion since I use the "Easy Does It" method as per the manual and I'm not changing my technique in this life. I only know my 150cc has been maintained but not pampered and runs better every passing mile. It pulls the steepest hills around here with much less effort than my CN-250 although I credit that to the 150cc weighing 125 pounds less than the 250.