those are all good links, read this one too http://forums.radiocontrolzone.com/s...engine+modding and i purchased a special bit liek this http://www2.towerhobbies.com/cgi-bin...&I=LXC678&P=ML for modding crankshafts, if you try anything else you will hardly scratch a crank, they are hardened steel and extremely tough, modding them has to be done carefully