From VicRoads: The list is primarily determined by assessing the power-to-weight ratio and engine capacity of motorcycles. If the power-to-weight ratio of a motorcycle exceeds 150 kilowatts per tonne or the engine capacity exceeds 660cc, the motorcycle will not be included on the list. Motorcycles may also be excluded from the LAMS list if they have other characteristics that make them unsuitable for learners, for example, being found to be overrepresented in crashes.

I believe the limit is 660cc in other states too.

At any rate, it's a bit of a moot point because all electric motorcycles are LAMS-approved and their acceleration is absolutely ridiculous.