</font><font color="blue" class="small">( ...I can add the following. On starting, white smoke is present, which clears almost immediately after starting. Engine runs smoothly, with no smoke or knocking. When warm, it starts easily....
...I may need to look into the issue of the timing-will get hold of a service manual... )</font>
I was looking back through your posts. I think a white cloud upon starting has to be either raw unburned fuel or less likely water vapor - from a bad headgasket, or rainwater down the exhaust.
I wouldn't describe the sound of these engines as smooth. More like desperately lean, knocking and struggling to hold rpm. Listen to the sound file at the bottom of my 'Yanmar photos' in the link below. After I close the compression release it strains against stiff compression then sounds extremely crude when it starts, and I think that is what they are supposed to sound like. If yours is a lot smoother that might indeed be a compression or timing issue.
From what I've read here it is unlikely to be out of time since the only way to adjust timing is to pull the fuel pump and remove shims. Did the previous owner attempt repairs?
