OLD EGT sensor and piston melt

Another lesson learned. Had about 34 hours on my EGT sensor (I have 2 VLR 100s, but used only one exhaust sensor for my Micron 5s-2t). Temps looked fine – in “normal” range. Wrong. Sensor was old and coated. This meant EGT was actually a lot higher than the read-out. Engine stopped; tear-down showed extreme heat on exhaust side of piston. Extreme defined as piston melt and fired ring. With new sensor (T12), I made a MAJOR adjustment to richen the LS and HS jets – but the new sensor showed I was still not rich enough. I hope this heads off any one else from making the same mistake…

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Makes me wonder if brake or carb cleaning the sensor would be good routine preventive maintenance.

I never use an EGT for anything but tuning, and the CHT or H20 takes priority. If they say it’s hot, it doesn’t matter what EGT says, you have your tune dead wrong.