Sooo did some testing on a bike over lunch. The stainless ebay thermocouple gets erratic when the bike is running (reads temps all over the place), but when the bike is off, it acts normal. did some reading and thermocouples work on the tiny tiny voltages dissimilar metals make when heated. makes me think the stainless is conducting some electricity from the spark plug and interfering with my the sensor readings.
im wondering if trailtech is using a fancy metal on the ring that conducts the heat, but not the interfering electricity of the spark plug... just spit balling.
edit: just got off the phone with trailtech. the technical support was really helpful and looked the specifications in the "drawings" he had access to. the ring is just copper. and it is NOT a thermocouple, rather it is a thermistor. (edited)