Yes two different stators and flywheels were used on the 1985 Honda BIG RED 250ES. I have had a few questions on this topic so I put together this blogpost to help identify which stator you have. Mitsuba is one of the manufacturers and NipponDenso sometimes called "ND" is the other. Note that the Mitsuba Stator will only work with a Mitsuba flywheel and a NipponDenso stator will only work with a NipponDenso flywheel due to dimensional differences.
MITSUBA STATOR and FLYWHEEL - The Mitsuba flywheel can be identified by looking at the outside diameter of the flywheel. You will find "Mitsuba" written on the outside diameter of the flywheel. A picture of a Mitsuba flywheel that came off of a 1985 Honda BIG RED 250ES is provided below.
The Mitsuba stator can be identified by counting the number of poles and measuring the outside diameter of the stator. The Mitsuba stator will have 13 poles and the outside diameter is 100mm. A picture of a Mitsuba stator that came off of a 1985 Honda BIG RED 250ES is provided below. Note that I wrote "bad" on the stator with a paint marker for my reference.
NIPPONDENSO STATOR and FLYWHEEL - The NipponDenso or "ND" flywheel can be identified by looking at the outside diameter of the flywheel. You will find "ND" written on the outside diameter of the flywheel. A picture of a NipponDenso flywheel that came off of a 1986 Honda BIG RED 250ES is provided below.
The NipponDenso stator can be identified by counting the number of poles and measuring the outside diameter of the stator. The NipponDenso stator will have 15 poles and the outside diameter is 103mm. A picture of a NipponDenso stator that came off of a 1986 Honda BIG RED 250ES is provided below.
As mentioned above the Mitsuba parts are not interchangeable with the NipponDenso parts. I am not sure which years the two different manufactures provided stators and flywheels for the 250ES BIG REDS. It is a good idea to take off the left crankcase cover to identify which stator and flywheel your BIG RED has before ordering any parts.