Instead of decking boards you could use scaffolding planks, cut to length as you describe. Not pretty, but you'd need fewer and they'd last a lifetime.
Not in the same league as luxury kit cars but in the mid-eighties there was a project called Africar. The idea was to provide a low tech vehicle that could be mass produced in developing countries, it was basically a plywood box with the drive provided by a Citroen GS engine and powertrain. The...
Oak grown in open parkland would have a spreading habit resulting in low hanging boughs with a natural curvature. Trees in closely spaced woodland grow straighter with fewer side branches. Hockey sticks were made from Ash cut from old coppice stools which gave them a curve at the base. Horses...
One of Jack Hargreaves excellent series - I can't remember if it's "Out of Town" or "Old Country" - shows how a wooden wheel is fitted with solid rubber tyres. Exactly as you describe a length of rubber tube is forced into a steel channel.
A simple method or sharpening fine-toothed saws is to find a hacksaw blade of the same tpi as the saw being sharpened. Clamp both in the vice with the tooth profiles aligned but the hacksaw blade slightly lower- just a mm or so. File each tooth down until the file hits the hardened hacksaw...
The 52cc Chinese engine is, as you say, generic and is used on many badged brands. Chainsaws, 5-in-1 multitools and Brushcutters are favourite applications If you can find a user manual for any of those it will give basic information regarding petroil ratios etc.
A very common problem on small 2strokes is gummed-up piston rings. The engines starts OK but has no power and "bogs down" during use. As mentioned earlier it's easy to inspect the piston by taking off the silencer and viewing through the exhaust port. Eventually exhaust gases bypass the gummed...
About 12 years ago I visited Australia for the first time (Sydney area, NSW). I was surprised by how much corrugated iron roofing remained, These were dwellings not outbuildings, it just seemed an odd choice of building material for the sunniest and hottest continent in the world.
The wheel in the first photo could be a Wheelwrights Traveller, used to measure the circumference of the iron tyres. Possibly Coopers used these as well. It's certainly a mixed bag - interesting though.