You can race a stock derbi ported with 15 carb and pipe in both classes, stockish and variated.
We could have created a stock class 100% stock, no porting no pipe but it's very slow and boring, no room for tuning, and I tried to launch that class in the past without any success cause most stock bikes on the streets already have an aftermarket pipe or a 15 carb and people didn't want to convert their bike back to stock just for a race, or mopeders commuting daily on a super stock moped didn't care about racing at all.
To me in the stocksih class with room for tuning and track performance, any moped using a stock factory engine cylinder and head ported with 15 carb max + pipe is fine, as long as it uses stock factory bottom end design no added material to the cases, stock ignition, stock transmission (variators, clutches, etc...) no after market performance parts (other than clutch springs) but mods to improve the stock system for track like lightening, drilling, cutting, welding are ok.
Some might argue that to win the stockish class with strict 15 carb + pipe rules no added material, launch lever, frankein stock motors, etc...people are gonna choose a dual variated moped and we're gonna end up with only light and quick honda hobbits on the track giving no chance for the Tomos 2 speed, puch 1 speed, peugeot single variated 2 tiny ports, etc... well if this is the case as the event grows with can always adapt and create sub classes within the stockish class based on transmission type. But for our 1st event, lets keep it simple and learn from it.
Also, during tech inspection we're gonna have to deal with few people bringing Frankein stock mopeds using the best stock frame and best stock engine parts from each moped brand eliminating all the factory design flaws and potentially making their bike the best weapon in the stock class crushing the competition.
To me it's a non factory stock prototype class that is for sure interesting and would showcase the skills of the best tuners using all stock moped parts available but once again belong in the stockish class as another subclass with separate rewards. I don't think it'd be fair to have them compete against a stock racer limited by the factory moped design and worked hard to get the best out of the factory motor with flaws.
Keeping it factory stock 15 carb = pipe would also answer the question of "which stock moped is the fastest on the track in the hands of a good tuner or good rider?"
Lets the brands compete against each other first, than if the event grows we can have more leveled classes based on transmission types or prototype engine.
is it before 1985, Honda, peugeot, puch, tomos, derbi, motobecane, garelli, minarelli, etc..?
Lets find out.
We can also ask during tech inspection if the motor is ported or just stock with 15 carb and pipe.
Ultimately we want everybody to be able to compete in the stock class which will be super fun, from the newbee Tomos owner to the master tuner frankein bike but we're gonna have to find a way to reward everybody in a fair way and encourage them to come back the following year.
When you have no chance at all racing is just not fun and too much domination kills a race event. "Strict" rules from the get go might turn off some moped racers who would want it more open and won't participate, but those rules are key for long term success and evolve as the event grows. (edited)