Getting a bit cranky

Previous features on this rebuild have highlighted the interesting condition of the internal oilways of the Triumph unit 350cc engine. Though I was never going to run the poor thing without a rebuild, I did pump oil through the crankshaft just to see if it would pass the vital lube – it did, and the mystery which surfaced later was ‘how?’

Just to clarify things a little, this engine is the type which uses a plain bush as the timing side main bearing. Oil is pumped from the tank through the case casting and on to the bush which has drillings through