Thought I'd interject a couple of quick notes for different temperature measurements.

The infared measurements will give you a general temperature reading from the cylinder. If you have a thermocouple mounted on the ring underneath a spark or glow plug, the thermocouple will give you a higher indicated temperature. With the thermocouple ring, you are reading the temperature right at the flame. Most likely the infared will give you a reading at the outer portion of the cooling fins.

For example, CHT at the cylinder head fins (via infared) might show 250 deg F. Measured at the glow plug, you will see temperatures like 350 deg F.

The bottom line is that if you are making measurements, they should be performed via the same method to give any reasonable answers. In many cases, you are looking for the delta (change) over different runs and using that as your health check, per se. As long as you do it the same each time, you will get the answers that you need.

Michael