Reading plugs and valves

A half hour flight should do it. However plugs only read the last thing, so if you land and taxi back for 5 min you only see the taxi colour not the climb etc. Engine gurus do a "plug chop" say tie the plane down run at full power for 2 min then turn off mags and close throttle, that way they do not change much.

These days a good wide-band O2 sensor does a good job and yo do not need the subjective skills. Yo can also read during flight at different power settings.

Do you have a particular sensor/product in mind that you can recommend. Having an inflight reading sounds somewhat interesting, too.

I have not done this for a few years, however I used a DIY kit from Australia that seems to be available now fully built...

https://www.tiperformance.com.au/products/techedge-2j9-wideband-o2-controller-lcd-display-kit/

You would need to weld a big nut 17mm if I remember correctly into your exhaust before the muffler, you can put a Blank in it when not using it.

The kit was battery powered an you can read the A/F ratio as you operate and take notes on where you are lean and where rich.

This is probably OVERKILL for an engine like the Rotax, all you really need to do is read the plugs and drop or raise the needle one step and see if it is better.

Rotax have already developed the engine to a high standard, unless you are making modifications to the engine you will not beat Rotax on tuning !