Kart less than 125cc ?

In my rf2 the minimun kart is 125cc... Mod or something to use 60 or 100cc Karts ???

Thanks.

 

I made a lower power version trying to match real times in the kart track I made.

The handling was very different compared to real life. Catching slides was very difficult compared to real life.

Hence I didn't put more time into it since I didn't like the first results.