Tune the engine for the best performance, starting with the first run. Never break in a gas engine rich. Do not fly a gas engine unless it has been tuned for the best performance, regardless of the stage of break in.

Gas engines are designed to be run in specific temperature ranges if they are to perform correctly. Too hot or too cold generates problems sooner or later. Too rich or too lean creates a condition that is too cold or too hot. So tuning and temperature largely go hand in hand.

The manufacturer provided needle settings for your use. Those are not to be relied upon for establishing engine performance, but are only enough to get the engine runing for you to then work on final tuning.

88C is a little cool but how was that result obtained? With a heat gun? If so you don't have a clue what the operating temperatures were while the engine was performing the most work while in flight. Obtain something that records operational temps in flight. Venom makes a relatively inexpensive high/lkow data logger that can be viewed after engine shut down. Temp guns are generally useless, so the 88C reading was probably not representative of true operating temps. If 88C was noted at idle after landing it only noted the state of the engine at that particular moment. 88C for an engine at idle is pretty good. 88c for an engine at wide open throttle in a climb isn't possible unless it is being drowned in gas.