Originally Posted by Toolmannz

Hi I have recently rebuilt a sirio .12 after a conrod failure the bronze big end bush had totally disintergrated.
After measuring everything up I discovered the Big end journal was 0.06mm
out of round,I dont know if this was a factory problem or a result of the conrod failure.After looking around for a replacement conrod I decided to make my own as the originals dont seem able to cut it.
As Im an engineer I remachined the crankpin and made a new conrod with a steeper knifedge profile to give it more strength and also machined 1mm radius around the pin ends to reduce fatigue at that point.The new conrod is made from alloy tooling plate Light and strong.
So far its run great .