As the title suggests there was this dent on my motorcycle and I'm not sure what happened. Any help is appreciated
As I pointed out in my comment earlier - it has been hit - a possible guess is that a pipe or somesuch has been dropped or bounced off the tank.
The possibility of suction being the cause is, imho, very unlikely given the curvature of the outer tank panels.
I can think of two possibilities to this:
- A vent line has become clogged and this has caused a vacuum condition in your tank, causing it to collapse. I've you've noticed the fuel cap being difficult to get off recently this might be it
- The tank has been damaged by some sort of impact, either something being dropped on it or possibly a car/truck hit it when it was parked