Rebuilt YSM-12 will not start after rebuild.

[jamie N]

But he says it is difficult to turn over compression?

Indeed, mine was also, but it doesn't take a great decrease in compression to make it 'not enough'. I can convince myself that it 'felt good' also, but it could be wishful recall or something.

 

[Boater Sam]

But he says it is difficult to turn over compression?

And there is a world of difference between being a bit hard to turn over and creating the compression ratio of over around the minimum 22 to 1 necessary to ignite the fuel.