So- a scooter will generally use a very simple powertrain. Most likely a 2 stroke engine with a carb. Most of its electrical and support components are usually not “automotive grade” by modern standards in construction or engineering. So there are many possible ways for this to happen- especially if the scooter was left on. However if we assume the scooter was not running, here is my most likely scenario:
The contact plate in the starter solenoid was fused, the solenoid failed in an “on” mode, or another electrical/ignition issue such as a false ground caused the starter to engage. The starter of most vehicles which do not somehow have their drive mechanism disengaged from the engine or transmission will allow the vehicle to move by motive power of the starter alone (not fast or far- and it wears or damages the starter, but in an operable vehicle with power to a PCM or with a carb you can get it fast enough generally to “push start” the motor if engaged.) the turn occurs because...
.. the kickstand is down and dragging on the ground which drags that side (like putting one leg down to make sharp turns on a bike/motor bike), and since the scooter leans left on its stand, it is already naturally inclined to left turns in that position due to physics. Fluke chance could cause such failures- as could manufacturing defect or poor design. Ultimately however the most likely primary factor for such a failure is operator error. If the design of the vehicle was inherently prone to such failure- such as not having a “positive shut off” mode to leave the vehicle so the driveline was disconnected- the operator selected the vehicle and should have selected one with safety features or parked it always assuming it could self start, so parked it in a way to prevent accidents. If the machine lacks safety features- you and your sense become the safety features- fine when you use “perfect judgment” at all times.
If the machine has safety features and they were not properly used- it again- operator error. If the features were disabled intentionally or through Improper maintenance- operator error. If the electrical and fuel systems failed amdnit was a fusion of the contact plate- it is again likely operator error. The plate will generally only fuse if either the electrical system is not properly maintained, if a current higher than rated is ran through the system such as through using a non specified battery or charging equipment, or through aging. If it is aging and wear- it should have been caught on inspection. So it is still operator error. Only if it were a sudden manufacturing defect- or sudden catostrophic internal component failure would it not be operator error. A vehicle is to be inspected regularly by a skilled technician- and any two wheeled vehicle or aircraft, or “extreme duty” vehicle should be inspected thoroughly regularly, and for all major safety systems each time it is used.
I would venture a problem with the centrifugal clutch. If it started to drag a bit heating it up the drag will increase. Letting it idle and and continuously slip will heat it up in no time. The clutch on my shovelhead did that to me in traffic and I ended up having no clutch at all.
@strongsad- I’m glad you are still here. That could go badly. I would agree that it is highly possible a clutch failure could cause this- and that this scooter most likely has a centrifugal clutch even if we can’t confirm model details. I placed it pretty high on my list of possible causes, but to my knowledge would require the moped be left running to have the effect and I couldn’t confirm it was running in the gif. But it’s a long list. A short coupled with atmospheric moisture can cause a bike to start on its own, and on a vehicle left running any number of possible driveline problems, brakes, sensors (if equipped), even the gear selector system with things like worn levers, improper adjustment, worn detents coupled with vibration... but yes. I agree your theory sounds plausible for a running scooter.
@creativedragonbaby- this is possible. Perhaps a strong magnetic field in flux triggered the electrical system, or a strong magnetic force moved the scooter... I can’t say I’d put it in the “top 10” things I’d investigate first if I was there... but, since we have very little fact or background I would say that our theories are on equal footing and yours has no objective disadvantage in possibility to the others- as for probability we are speculating so effectively the probabilities are equal on Schrödinger's Scooter- it is whatever we say it is until we have observable proof to the contrary.
The contact plate in the starter solenoid was fused, the solenoid failed in an “on” mode, or another electrical/ignition issue such as a false ground caused the starter to engage. The starter of most vehicles which do not somehow have their drive mechanism disengaged from the engine or transmission will allow the vehicle to move by motive power of the starter alone (not fast or far- and it wears or damages the starter, but in an operable vehicle with power to a PCM or with a carb you can get it fast enough generally to “push start” the motor if engaged.) the turn occurs because...