As my engine started knocking , I thought I swap engines. The old one was a mk.2 bottom with a gsxr 11K top end, new one a stock bandit mk.1.  As I wanted to keep the mk.2 loom and digital k5 bandit clocks, I had to drill the output shaft.  After 2 hours with a box of high quality carbide drill bits I was only 4 or 5mm in.  I decided to have a break and search the forum for an answer. Same results, everyone having a go, most giving up as case hardened steel is a right bastard to drill.