I also found that bump starting was every bit as easy as a 125 2cycle. It really did make a different bike out of it. I find it hard to buy off on ring seal making such a dramatic difference in the charector of this modification. Of course if you are afraid that you are gonna choke half way through stroke, and get your shoulder dislocated...and never actually tried to start it by hand 'cause you be skeered (lol)...then I can see where one would have the perception of it being a hard task. The recommendation for shim change size is a guideline. It is intended to give you a window of what size shims you should probably have on hand when you start the change out. It is assuming your valve lash is set proper within specs. to begin with. If all you did is install shims that concur with the recommendations, you need to go back and go through the valve lash procedure properly.