Bought myself my first lithium battery a couple months ago. Pretty neat. Haven't been on many rides with it yet. Yesterday was a solid day when I noticed what the volts were.
What are the voltages supposed to be though? Mine kept going down as low as 12.9 for a split second, to a high of 13.7 for split second. Floated between 13.1 and 13.5 for the most part.
is 14.2v not a thing with lithium batteries?
See if you can find a data sheet for that battery. There's some variation on what resting voltage constitutes 100% state of charge. Once you have that, you can check battery voltage with the bike off and have a better idea about its state of charge. There are also generic charts available that should be fairly close to your battery's specs.
Lithium based batteries typically accept whatever amps a charge source can deliver up to at least 80% SOC. What you described may be due to your bike dumping all it could into the battery, with the voltage varying because of the bike's output. In some setups (RVs & boats), a lithium battery bank can even put enough load on an alternator to destroy it.
Unlike lead-acid batteries, lithium batteries have a very flat discharge curve until they drop below 20% or so. Also unlike lead-acid, they have very low self-discharge rates, and prefer to be stored at 50-80% SOC.