I want to use easy to obtain parts so I selected the standard GT2 timing belt and pulleys used in everyday 3D printers. The crankshaft to camshaft spacing works out pretty well with a 320mm belt with a 24 and 48 tooth pulley. The bore will be 1" and 25mm. I live in California so I use the imperial measurement system, but wanted to try to design using Metric. I set off laying out the engine in Metric and soon found that my mind does not work in whole numbers, only in fractions with denominators of 16, and 32. So I reverted to designing in imperial. But I am determined to expand my brain and try to work in metric so I designed the engine in imperial, then designed another variant in metric. Not a metric conversion, but truly metric throughout. So I ended up with two sets of plans, one with a bore of 1" and another with a bore of 25mm. I am calling them the Lynx 90 (.90 cubic inches) and the Lynx 15 ( 15 cubic centimeters) in homage to the late Malcolm Stride. The valve train seemed the trickiest so once I figured out the Crankshaft to camshaft spacing I looked at the valve train. Something like this:

This is what I have ended up with:

I'll start by building the Crankcase Assembly.

I bore the large crankshaft hole in the block:

then square the block up on the mill zeroing the mill to this hole:

Drill and tap the holes, then machine corners off:

that is the crankcase done:

And now it is on to the front crankcase:

Next will be the cylinder sleeve and cylinder............................................