Update so far: 
Cleaned the carb out spotless all valves, needles, choke port. Also replaced the spark plug cap, spark looked all good, 
put it all back together and  kicked it over a few times then she went. i let it warm up then killed it, kicked it over and it started sweet as always when warm.  
did this a couple of times over half hour, all good! 
i then turned off fuel as usual, put it away and thought i'd won. 
two days later went to start it, fuel on, choke on, a couple of kicks, left it for 2-3 mins then carried on trying with not even a fire up.???????? 
I'm now waiting on piston rings, see what happens with that?