The two halves of the conrod were taken down to overall size by flycutting the 2014 grade aluminium; the rod part was drilled and tapped, the cap drilled and counter bored for the screw heads. I made up a couple of sacrificial brass screws to hold the two parts together so that the CNC could do the outer profile in one without worrying about the screws. The big and little ends were done on the manual mill then a simple block with two tapped holes and a couple of top hat bushes to hold the rod down. And then press ‘go’.

The carburettor body was carved from a length of 20mm 6082 aluminium. After facing off and drilling the centre hole it was over to the  CNC using that to cut the elliptical flange and drill the two mounting holes under size.

I then tapped the holes so that a piece of 1.5mm thick stainless steel could be held and cut to a similar shape, this was used as the mounting flange for the exhaust.

It was then back to the lathe to complete the turning of the long central section which was done with a 1.0mm radius grooving tool as I wanted a fillet in the two internal corners.

Then with the part reversed in the chuck the same tool was used to form the inlet spigot.

The remaining 20mm dia section was then milled down to a 12mm square and a hole reamed through it for the carb's barrel to rotate in. The rough looking area at the upper far side of the hole is a tapped hole for the slow speed adjustment screw.

Not the best photo of the barrel which has been cross drilled for the airway and a flat milled at right angles for the above mentioned slow speed adjusting screw to bear on.

The rest of the parts were fairly straight forward turning jobs. For a while I have wanted to use a jam jar for a fuel tank as a lot of trawling through e-bay finally found some suitable jars that could be built into the design. The throttle is controlled by twisting the jar rather than having a separate arm though one could easily be added.

Part one here  Part two  Part three  Part four  Part five  Part six  Part seven