Valve lapping

Craig at Scooter Works told me I had to 'lap' my valves and explained how it increases compression.

I bought the lapping sticks and the grease and went to work while watching old episodes of Star Trek TNG.
Removing the spring and then replacing them was very quick this time.

I first used the course and then the fine grit. The results look good. The top one below looks good.

A lot of improvement can be seen on the right one. The left one has not been done yet.