RE: Tower Hobbies .46
Trav,
An IR thermometer photo, is probably what I would put next to a dictionary definition of 'booby-buy', as far as model airplane engines are concerned...
It 'lies' to you frequently and anything it is claimed to be capable of telling you, can easily be determined without it.
If your engine is set slightly rich of peak (i.e. it can be leaned further, increasing RPM), it is at its proper operating temperature; regardless of what its numerical value actually is.
And frankly, if using such a device 'determines' any point on the air-cooled outside of any sport glow engine is at 340ºF; and the engine is running properly, at a smooth two-cycle, it is faulty for sure (the IR Thermometer; NOT the engine).