I'm gonna guess "moped" unlimited, I think back in the days we set the limit at 99cc, but the biggest engine I remember seeing a the time was a dual variated 90cc Stage6.
They'll probably fit any fast mopeds 50cc and above (but separated for the podium) within the motorized bicycle unlimited class including some monster 212cc 4stroke engines... those rip, the torque and power to weight ratio are insane. I test rode one of them 5 years ago... fun and scary at the same time :)
I've always competed in the unlimited class or any class with 50cc engines only. Never actually raced bigger engines, not even 70cc moped kits.
I upgraded once my Puch Maxi E50 cases inducted race bike from an AIrsal 50cc H2o cheap scooter kit which performed pretty good, to a Metrakit 77cc Pro Race kit, but don't remember personally hitting the track with it during a moped race event, I think I played with it in the streets and sold the bike.
In other words I'm not super attached to the cc rule, I've always competed against much bigger engines, or even faster bikes like those mini moto Kawasaki KX65 or KX80 didn't win any of the races in their classes but the challenge was always fun.
I'm just excited to finally bring something bigger than a 50cc moped at the track. But I'll probably enjoy lifting the front end during the tuning phase in the streets of LA, and probably hit the freeway at some point for a top speed run... people love seeing that shit on social media... "what's your top speed bro?"... we'll bring some footage :) (edited)