Finally the wait is over, and I have realised the cylinder jig. This is the first attempt, at making a multi purpose jig that can hold the cylinder in three positions, one for the exhaust valve rework, and another for the inlet valve, with the middle position being the overbore and combustion chamber rework for the larger capacity engine.

It was fitted to the larger CNC mill today for a test fit, and make sure the extended tooling didn’t catch the walls of the standard cylinder. To machine the valve seats I need a special carbide tipped tool about 30mm or so diameter, so that the tool spindle doesn’t catch the sides.