Super bike question

[chromedawg]

I caught sport bike fever at the tender young age of 65. I massively enjoy watching the races on tv. I don't understand why Ducati is allowed to race a bigger engine, is there some kind of air intake restriction or something? I would really like someone to explain this for me.

[sanfret]

They are running a different motor configuration, a 2 cylinder versus the other folks running 4 cylinder machines.