I've got a spark plug ring temp sensor. Now the trail computer I've got says air cooled engines read hotter than liquid cooled. But it doesn't say how hot is dangerous. I also know that under the plug is probably the hottest point in a air cooled cylinder. All I know is 260 to 300 is normal at trail speeds and upwards of 340 occurs at 55 to 60mph road speeds prolonged for very long. It never seems to act hot as far as metal "tinking" goes, but I also know that those temps in a liquid cooled engine are catastrophic. Does anyone have any "rule of thumb" on this sort of thing?