Under seat lock
There are a number of locks that fit - it is just a question of the radius of the curved part - but you will probably have to stow the solid locking chunk somewhere else. However if, like me, you use the lock everytime you park anywhere (for insurance purposes) you will have to master the art of getting the seat off (easy) and putting it back (very difficult.) After 18 months I have given up and stick the lock in my tank bag on a piece of plastic cut to fit.