Spit test isn't accurate. You should place your tongue against the cylinder head. If you can keep it there for 3 seconds before it burns your engine si running at correct temperature, if it burns instantly, too lean, if it takes longer than 3 seconds for it to burn, too rich.
Its just that easy.
The best way to tell if you are overheating is you are experiencing performance loss at full throttle. I ran my bike for 15 miles up a steep Colorado mountain last summer and my exhaust pipe was RED and engine head changed to a duller grey color. Did I overheat my engine? Apparently not, it never seized and kept chugging along without any loss of power or speed.