Yz 144 Case Mod For Cylinder Clearance

ok i was told to tape off the crankcase and use a dremell to make room for the cylinder skirt on my 06 yz 125,im nervous about messing this up and takeing to much off or no matter how carefull i am there will b some shaveings getting into the motor.Was thinking about spliting the cases and haveing a shop mill them.While i have everything apart i would change all the bearings to ceramic.any thought on what route i should go? i know some people here dont like cermaic bearings but i know the guy very well who owns the bearing shop and he has put them in everything for the last 3 years from top fuel drag bikes to pit bikes and not 1 prob from any bike he has done :whoa:

what bearings like dirt??if i keep my tranny oil and air filter clean how can the ceramic bearings come in contact with dirt??