Had a bit more time today to play around with the Supercut.
Firstly, crimped a proper terminal onto the spark plug lead and put a boot over it.
Secondly, pulled out the spark plug for a look. Piston was moving up and down perfectly fine but could see one of the valves was open and not closing through the spark plug hole. Decided to remove the cylinder head and have a look inside.
Bore is very shiny and maybe lightly scored, very slight ridge at the top so long-term, probably needs a hone and some rings.
Exhaust valve was stuck open so I gave it a moderate hit with my hand which pushed it closed. Pulled the cord and repeated this a few more times until it seemed to be opening and closing freely.
Not ideal but I didn't have a head gasket here and upon inspection the gasket on it looked in reasonable condition so gave it a light smear of aviation sealer and reassembled, torquing the head to 30nm (spec is 26 I think) because my torque wrench doesn't go any lower.
Gave a few hours for the sealant to hopefully cure a little bit then splashed a bit of fuel in the tank, closed the choke and pulled the starter. Engine started first pull, was a bit smoky but seemed to clear up after running for a few minutes. Pleased to report that both the blade and drive clutches engage and disengage. Needs a new seal around the carby bowl as this drips slowly and the reel and bottom blade definitely need a cleanup, but will change the oil, replace the spark plug, clean the air filter and leave the engine alone for a while I think.
