Hi belgiantwin,
the rotor should not be magnetic at all. Alternators with an exiter coil are different than the often used alternators with a magnetic rotor and only one set of coils.
E.g. B3 and later models have this other alternator type.
Don’t get that mixed up 🙂
You may download a manual for the B-models at
http://kz750twins.com/?p=15
It’s a 186 MB file !!!
At around page 175 you will find all the measurements described which have to do with alternator and R/R (rectifier/regulator).
Cheers, Michael
