[Berkyboy]

As far as I know Robbie's bike may be a 250, stock the 300 and 250 both use the same crank only the cylinder, head and piston are different.

Unless the French relocated the crank pin and/or used a different connecting rod and/or/and modified the cylinde/head nobody's 100% sure as we never had to go inside the motor and I don't know if Robbie did either.

Stock 250/300 and 200 cranks all use the same connecting rod, mainly the crank pin location is the difference which obviously changes the stroke.

All we know for sure is Robbie's motorcycle's paperwork (vin number and engine number) indicate it started life as a EC300 and during the "French" buildup they used a stock 250 piston as well as a 250 cylinder and head.

I believe his bike was Nambotin's when Nambo' rode in the WEC Junior Enduro class, where displacement was not a factor and for those races they may have thought they needed a 250 instead of a 300. Or it indeed could be a hybrid (275) not really sure.