Combustion temperature

Is there a way to measure combustion temperatures when choosing AFR

EGTs in the exhaust is the only remotely inexpensive way I know to do it. Harley, on the air cooled motors, have a screw in head temp sensor but it would be of little value on a water cooled motor. There are washer like thermo couple things that sit between the plug seat and the head but I have not played with them.

I tend to set AFR with what makes the motor "Happy"

Andy

As Andy mentions, it's not possible (at least at the hobbyist and semi professional level) to directly measure combustion temperature. EGT will give you an indication of what the combustion temperature was (EGT is understandably going to be lower), however EGT is also affected by aspects such as the ignition timing and the placement of the sensor in the exhaust system.