Yes, check your state laws. But I think even if you got a ticket, you could fight it in court and probably win. (if the judge was reasonable anyway) Clearly explaining that your bike would not trigger the lights and that you waited through at least one full cycle of signals plus what ever it was when you first approached, made sure the intersection was clear and safe before you proceeded just may be enough to vindicate you. But you must actually do the waiting through the light signal cycle. (somebody may actually see whether you did or not)
And the lights trigger not by weight of the vehicle but rather by the metalic mass of the vehicle. They work like a big metal detector; if there is not enough, it won't trigger and the sensitivity is such that it will not detect vehicles in the next lane over requiring the vehicle to be very close to the sensors and with enough metal bulk to detect and activate the lights.
Those magnets they sell may work sometimes if they disrupt the magnetic flux of the detectors enough and cause it to trigger. But even that may not enough depending on the detector sensitivity. IMO, they would seem to be a waste of time and money and you would be better off to just proceed safely and defend yourself in court if needed.
If they are unreasonable about it, then all you could do then is avoid left hand turns like the plague (usually within city limits) at those type of lights. Alternatively, you could fight for your cause in the courts to change the laws or to allow waivers for small vehicles such as scooters and motorcycles. I'm pretty sure the courts are aware of the problem if they have such systems in place in their towns and that in the interest of safety such accommodations would be reasonable and beneficial to the community.(YIKES!!! Starting to sound like a lawyer/politician)
S.E. Michigan Darkside Rider
4 Honda NSS250 Reflex Scooters and 1 FSC600A Silverwing scooter.
"Great ideas often receive violent opposition from mediocre minds." - Albert Einstein