Hi Chris
Undo the 4 head nuts (circled), then take head off.
Then pull on the barrel, it will separate in location I have marked (the studs are screwed into crank case so wont move)
you will be left with the 'crankcase' with a conrod an piston sticking out
Easier to get the lower g clip (which locates gudgeon pin) off the piston with motor off the deck, but is achievable with it on
You need - head gasket, base gasket (can make base gasket from gasket paper but not head gasket)
Don't buy anything till you get the barrel off - as if that is deeply gouged you need a rebore, oversize piston
