So after suggestions of what could be causing this motor not to run. It has always been a bit down on power and it was dropped in some water not long before it stopped all together, I obviously replaced the oil straight after it was in the water.
New carby, piston, rings, gaskets including base and head.
I've made this video that goes for 4 minutes showing thinking like me checking the spark, turning it over with the tappet cover off and talking about the timing etc
https://www.youtube.com/watch?v=Ge2sDQOxkE0
