Hi thanks for reply,just about to call the men in the white coats for this one, started off usual problem ,went to start ,turned 1/2 revolution then stuck,long story short solenoid valve coil O/C, fitted tap in fuel line, did oil change all ok,now latest prob' is runs for 30 mins cutting,the acts like its got fuel starvation,whack open choke and it runs at fairly high revs for about another 5/10mins ok,the just dies,wont restart, leave it for 25/30 mins starts ok and runs again for 30mins, ok so far done:- carb,fuel filter,cleaned out tank and run with no cap on,new fuel lines,new plug,new coil assbly,pulled head and checked valve seats (lapped in ) ,blown out all fins nooks and cranny's with air line,run without hood on to see if its heat related,disconnected all safety switches/bypassed, taken off exhaust and checked for blockages/run with no exhaust, only odd thing I have noticed is that exhaust valve guide is higher out of top of head than inlet one,tired tapping it to see if its loose but not,so before my wife calls the men in white coats can anyone offer suggestions PLEASE