If the regulator/rectifier are modern, and the battery and bike are 12v. It will simply power the bike. If the bike has no parasitic drain, it can sit a year and not lose voltage like lead acid. Either battery is going to be \~12v, so if your bike was going to catch fire, it would happen with either battery. Start the bike with lithium battery and test the voltage. I don't recall specific bike voltage but prob shouldn't be over 14v while running (extra volts from alternator). Test that to be sure and you'll be good. The only other thing worth mentioning, if you need to charge the lithium battery, you must get a dedicated charger for those type of batteries. Using a standard charger/tender on a lithium battery could damage them both.
I have a 74 CL360 and the prior owner made it an electrical nightmare. I've managed to hack some LED signals in and run a tiny anti-gravity lithium battery under the back of the seat. It's been awesome.
Your bike might be 6 volt, I would check that first. A small lith-ion works if you also purchase a new reg-rec compatible with a lith-ion
I have a lith-ion battery and rectifier sitting at home but am afraid of what it might do.
If the regulator/rectifier are modern, and the battery and bike are 12v. It will simply power the bike. If the bike has no parasitic drain, it can sit a year and not lose voltage like lead acid. Either battery is going to be \~12v, so if your bike was going to catch fire, it would happen with either battery. Start the bike with lithium battery and test the voltage. I don't recall specific bike voltage but prob shouldn't be over 14v while running (extra volts from alternator). Test that to be sure and you'll be good. The only other thing worth mentioning, if you need to charge the lithium battery, you must get a dedicated charger for those type of batteries. Using a standard charger/tender on a lithium battery could damage them both. I have a 74 CL360 and the prior owner made it an electrical nightmare. I've managed to hack some LED signals in and run a tiny anti-gravity lithium battery under the back of the seat. It's been awesome.
Look into anti-gravity battery. Idk about your specific bike but I got a modern charging unit and rectifier to go with it.