To throw in a personal experience, not scientific opinion; I have one on my WR250R and love it, but the bike has a more modern charging system and I don't ride it in cold weather. I love that you don't need to charge it if the bike has been sitting months, it'll fire right up.

On the other hand I had one on a snowmobile and while it didn't do anything dangerous, it developed an internal short that robbed power off the magneto when pull starting (and of course wouldn't hold a charge for the starter). That was a fun week of diagnosing, chasing wires around, testing the voltage regulator and ecu everything else before finally unplugging the damn battery and having it start right up.

In reply to post #10. Sounds extremely scary for sure.

I’ve had a lithium battery on my Cafe virago for years with no trouble. My opinion and it is just that is lithium batteries get a bad wrap from LiPo versions found in very high energy demanding devices like RC cars and cell phones. Most lithium batteries for automotive use are lithium ion and are better for safety. Although don’t drill them….

I used to do a lot of RC vehicule stuff with many kinds of power sources, had a huge power supply unit and a couple of intelligent charging systems and multiple banks of chargers. Had some 'puffed' batteries and got a few 'hot' scares but never set anything on fire. I guess on the older magneto and points engines I can see some of the difficulties but it would be possible to wire in some kind of 'safety valve'. It does drop to freezing here in the mountains in winter. I could install one and keep monitoring its status but I think now I'll leave that for much later on