Am always tempted by some of the more exotic racing fuels but am happy for the moment to stick with normal pump fuel. Inspite of all the worries about using unleaded all seems well with the valve seats in that regard.

 

Winter work is something I feel you have to stick at as if you leave off too long you forget what bits you were working on !

 

managed after very many years to get hold of a copy of that wonderful book by Philip H Smith " The High Speed two-stroke petrol engine" . As a young man I was enthralled by it when borrowed from my local library and since many of my generation started out on two strokes I am certain others retain a soft spot for them. This page above illustrates a range of piston crowns and for good measure Smith included a Manx Norton one on the bottom right corner. 

 

 

 

I was significantly lighter in my younger days and so the scale of those lightweight machines was an added attraction. The popularity of the disc intake valve provided the answer to a lot of the issues of timing racers using the two stroke principle. What a pity that emission laws have all but made them disappear. There is certainly a need to redevelop the two-stroke in harmony with current emission thinking and technology.