As we are all aware, there's no helmet lock on the bike so after market is the only option. After looking for a lock to suit my requirements I gave up and paid the eye watering price commanded by the Honda Accessory (AUD$95)
The lock is made by/for Kitaco from Japan but actually made in Thailand. Here's a shot of the package:
And the actual components (pic from the net). There's a lock section and an adapter that replaces the bar clamp, plus keys and an extra long machine screw.
Tools need to install are a 5mm hex bit and a No3 Phillips head bit and any handles/drivers you prefer to use.
Installation was as simple as removing the front brake clamp from the handlebar by unscrewing the 2 x 6mm socket head screws. The lock adapter and lock are then put on and secured with the new long screw and one of the original socket head screws. In all it didn't take as long to do as write this post.
However, after fitting it as shown in the Honda Accessory web page
I decided to put it on the left hand side as that's where I get on and off the bike. So here it is fitted in the final position.
A check for clearance on full left lock shows that it won't connect with the tank.
It's quite easy to use and the helmet can be hung from the lock, or sat on top of the bars which is what I usually do.
As I mentioned, Kitaco make these but it appears that the 1" variant is only available via Honda at the moment. Hopefully as the CMX500/300 matures there will be more accessories at reasonable prices.