Next I finished off the front part of the cylinder; fitted studs and gasket to the front cylinder cover.

Solved a problem of slight axial movement of the crankshaft. I fitted another spacer, this time between the eccentric and the bearing. Unfortunately, another problem seemed to have cropped up, an annoying knocking sound when the engine was turning on air. If I turn it manually the knock is not there. So I guessed the knock was generated during the power stroke. I suspected that it had to do with the crankpin. Made a tighter temporary pin from aluminium to see if it helped.

Seems that the 'knock' has reduced.  So I have to remake a new crankpin. The diameter of the original pin was 6.43mm and the temporary one is 6.47mm.

It took three attempts to get the crankpin diameter just right by polishing to the final diameter. The one on the left is the original and the one on the right is the third attempt. 

Decided to add something which might be used for a barring bar to turn the flywheel with.  I relied on a couple of photos from the internet to make it.

For pipework I used a 6mm OD copper tubing and a commercial pipe bender to do a 180 deg. bend. I had already tried it out with an 8mm tube and it gave a nice bend. So I thought a 6mm tube should not be a problem. How wrong I was! I could not get a decent bend.

I annealed the copper pipe and managed to get a good bend. I soft soldered the pipe to a brass flange which eventually will be bolted to the inlet cover on top of the cylinder.

Cut it to size and did a trial fit.

I used that piece of scrap copper pipe to do a test with the string.

The finished pipe. I noticed after I sealed the string with superglue that very fine bristles from the string stood out.  Fixed that with a light sanding.  Next, I applied two coats of undercoat white paint and in between coats gave another light sanding.

I also made a 90 deg. adaptor which will be screwed from below the base under the copper pipe.

Drawings here

Part 22 here  Part here