After reassembling the engine always reset the tappets at just before TDC ....YS engines like tight clearance on the tappets.
A word of caution, my 170cdi gave me grief on and off for years, sometimes running perfectly for months and hundreds of flights, then it'd drive me insane for a few months.
To cut a very long story short, that engine (mine anyway) did not like the cold tappet clearance set below about 0.06mm. (YS manual says 0.0mm-0.1mm)
I'm running my 200cdi clearance at 0.08mm and will tighten it up in after a few more hours and see if it stays running trouble free.