On both sides?
As I mentione is should be a .15 if it is normally mounted without modifications.
Has it a side or a rear exhaust?
You can messure the bore/stroke to be sure.
But the engine is already some years old, If you want to mount a rotostarter I think it is wise to go to a LHS and try some.
Speed is only fiction but a 130+km/h MRS4 is for real.