my mgt 8.0 gets pretty toasty like 270F but runs great with a good smoke trail and no signs at all of a too lean setting, but my JPX and Nova p5X probably run 220-230.

the only time i use a temp guage is when im breaking in a engine or, if im new to the engine, other than that, sound, smell and smoke trail is all i need to dial it in.

are you sure your not overfilling your tank and its not just the tank back-pressure bubbling it up like a hookah?