You can pound a square peg in a round hole. But, should you?
Lithium battery tech uses different voltages than Lead acid type. So, in technical terms a VR (Voltage regulator) for lead acid shouldn't be used for Lithium.
The cross match will never be ideal. But, it may "work" well enough for you to be comfortable with it.
Your lithium battery will have a spec for "never exceed" voltage to it. It will also have a never go below voltage for it. I don't know of any Motorcycle VR that will protect the battery from too low voltage. Like if you leave the lights on, expect battery damage of some sort. Lead acid batteries don't like this much either but, they can stand abuse better than lithium.
Is your VR adjustable? If so adjust it for 14.4 V max and your lithium should be happy. Many Lead acid VRs have fixed output max at 14.5 to 14.7V. Technically this is hard on lithium. It may survive a good while with this, or not, as it is is outside manufacturers specs. You take the responsibility. It will unlikely blow up. It may just die prematurely and leave you stranded somewhere. Or maybe not. It's undefined territory. Feel like a pioneer?
Added to the question is what your bike can do in the way of power distribution. The VReg can only respond to what is reported to it at it's terminals. If between battery and VR there is a voltage drop of 2 volts. The VR will try and make its output 14.5V. If the battery is actually at 16.5V, the VR won't know it, and cook the battery. Lead acid battery tech is more tolerant of this than lithium. But, you won't be doing a lead acid battery any favors by doing this, either. The wiring of the bike is another component of the charging system that must be scrutinized.
Cheers,
