Yes very clever man that.......I remember speaking to him on several occasions when I built the twin racer years ago, and he told me some of the detail in building Ian Boyd's engine.......The rework he did to the cylinder head was something else.......Not sure if he changed the valve angles but he raised the ports and squish band the chamber plus much more.......He said the head was like Plasticine and soft as butter.......not sure why they didn't re heat treat it.....but that is risky in itself.......They bought some super expensive piece of super rare material to machine up a conrod from.......i know it cost Ian a huge amount of money to build.......probably done in a similar way to Geoff Clatworthy's ES 4 Norton single........almost untouchable those machines.......500 single pushrod engine, with full fairing, 107 Kg's, and over 60 HP........A very tall order to beat that.