You know how all this could be fixed?
Just race in the RACE super series. lol
Maybe John can clarify, but when I used to race with the 125 Can-Am cup series....I dont remember a spec tire. It was CHEAP, and there were a LOT of us. I remember 55 riders 14-19 (and some Old fogies as well) on the grid, because all we had to do was buy a 125 honda, Yamaha, or Aprilla, I remember a guy having a gilleria too. There was really no difference apart from the rider. (Until Honda Canada fielded an RS125 for Chris Peris....dont even get me started on THAT)
If you want to get more people involves, take the manufactures out of the equation.
Open 400
51Hp limit. (CSBK has a dyno)
That way the RC390/R3 can only have limited upgrades, But say a CBR300r can be much more modified to compete with the bigger displacement bikes.