Its not uncommon to see a build up of pressure with the rad cap off because you are lowering the boiling point when you remove the pressure cap. Think about the times you fill a cooling system then run it without the cap usually end up with a sudden shower. That,s not to say that maybe there is not a bit too much bubbling going on there but also not that it particularly is an issue either. With the coolant lowered and temperature rising that bubbling could just be due to expansion of both air and coolant in the rad. With the amount bubbling through the solution with out changing colour however I would say there are no combustion gases entering the rad. The fluid is very sensitive and changes colour very easily if there is any combustion gas existing. Matter of fact we would take a breath sample with it to see if the fluid was still good.
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I used this brake light modulator BackOFF™ XP Brake Light Module - Signal Dynamics . It allows the option of adding a fused switch which I wired directly to the battery. Mounted the switch under the seat, which I can reach while riding if necessary. Since the switch is wired directly to the battery, it allows operation even with the bike off. Granted, it doesn't do any good in the front, but better than nothing. Thankfully, I've never had to use it.
Taking this one step further, can you use the module to trigger a relay that is wired to the front turn signals? May need to isolate the turn signal relay from the circuit but maybe not...