Coolant is bit of a science. Too much/little it can freeze still

, too little it can boil. 50/50 is the best to have in it as it also lubes the seal surfaces too. The green stuff the best to see the differences in.
In my shop I buy full strength and mix it with distilled water in a clean peanut clear plastic jar and added just that much at a time filled up the radiator first to the top, then filled the reservoir to the full mark ran it till it was showing on the gauge to be in the middle, then shut it down to cool completely, then checked and literally added maybe a few ounces then did it again and added again. I did this about 4 or 5 times then when I rode it in the warmer weather and it actually got up to temp running like that I added 1 more time again. It has not moved since. Just how I do it, and it has worked for me.
I do this yearly on all my vehicles too, since I hate the cooling system getting grimed up in the heater cores. Since the bikes have heater core size radiators, it makes since in my head.
One other thought make sure you check on the center stand every time or the side stand, mine does not have a factory center stand so I check it on the side stand so it is consistently the same "checking".
If it is not running hot just know that is considered an expansion tank, so the coolant can expand, when it expands it will make noise and it does expand thought the radiator cap. you may need a new one if it is not running hot but burbling a lot, just some thoughts.