Aaron, where does it say that?
All I can find is:
Mini and Micro Appendix:
6.9 j) OLD CARB – “Main jet is free but limited to those supplied in the Rotax Micro MAX jet package (ROTAX part 281476, which includes main jets: 115-118-120-122-125-128-130).”
Right below, it says for the NEW CARB “Regulation for XS carburetor: Section 6.8 fo the 2015 RMC Technical Regulations apply.”
In the RMC Tech Regs:
6.8 talks about the intake silencer, so I’ll assume that it should be 6.9…
At 6.9 there is nothing that talks about main jets.
So, it looks to me that:
1) NEW CARB – main jet is open.
2) OLD CARBS – main jet is restricted in MicroMax only.