This was the first time out with an EGT probe on a can muffler and the readings were not what I expected. Got only a 180 degree difference from low to high readings and very gradual changes. This doesn’t seem right.
What were you readings? Is this a Mychron EGT probe?
I assume you have the probe in the tube between the header flange and the can. The probe should be inserted to the center of the tube as well. If you have both of these conditions you should be seeing temps up to 1180-1200F down to ambient.
The Mychron EGT probe reacts pretty fast so you should that reflected when working properly. You could take the probe out and with the gauge on wave a propane torch back and forth over it. If the temps go up and down the probe is probably good and there is something not right with the install.
the readings from several runs ranged from the 870’s to the 980’s. In Race Studio, the egt traces look the same with a lazy change in temperature.
A Mychron4 was used, but not with the short Mychron sensor. The sensor used was longer and easily reaches the center of the tube between the flange and can. Have used this type of egt probe in the past, many years ago, on kt100 pipe engines.
It’s still early in the examination of the session. We weren’t trying to get everything out of the engine but expected to see greater and faster changes in temp.
It sounds to me that you have a sensor going bad they usally start getting lazy and are slow to respond. As I said earlier our sensor will climb to about 1100 degrees as mark said. They do however look lazy on a graph compared to your RPM. Typically on the track I will see a range of mid 800’s to mid 1100’s. I look at the longest straight in the track and by seeing that the temperature climbing the whole time I know the engine is burning fuel and is not lean, if the temp. starts to cool before the end of the longest straight (before lifting out of the throttle) I know it stopped burning fuel and went lean. The secret to max power and engine longevity is to be on that edge of lean and still burning fuel (climbing temp) without running out of fuel (cooling temp) running lean.
Another possibility is that your so rich that the engine is staying cool due to not burning all the fuel cooling the combustion chamber and that will keep the cylinder cooler because the unburned fuel absorbs the heat from the cylinder/piston and exits through the exhaust.
Rich=Cold, Lean =Hot, Lean is also faster up to a point, Lean is also dangerous to the engine causing seizures.
Most 2 stroke guys will tell you the engine never ran faster then what it did right before it seized.