Reply To: Smokey F.15 – well, thats odd

Home Forums The Machinery Forums Pedestrian operated machines Smokey F.15 – well, thats odd Reply To: Smokey F.15 – well, thats odd


Running the engine without the crankcase breather valve could be counter productive in that while providing an exit for the air displaced on the downward piston stroke, it should seal on the upward stroke creating a negative pressure area in the crankcase to keep the engine oil tight. It’s possible that some of your oil burning is due to the ball valve not sealing properly and not creating that negative pressure.
The F15 used two versions of the breather, the ball one that you have and a (later?) poppet valve similar to that used on the F12 Sloper. That was integral with the valve chest cover, so is an easy swap. Paul at Meetens is the man to advise whether it might be worth doing.

I too had noticed the difference in the amount of useful information provided in the earlier Mk series manual compared with the F15 one that I posted, but in fairness it does mention oversized valve stems and reaming – buried in the text at the foot of page 13.