Is the ignition unit, the one under the tank, the same on a k75 as on the k100 just with different cable connections on the plug?

or are they different

thanks

The BMW OEM part numbers vary from model to model with some variation for specific markets too.

12 14 1 459 021 most K75

12 14 1 459 018 most K100

The K75 being a 3 cylinders, you cannot use the ignition computer on a K100.

You could try, if the connection was the same, which it isn't, but it would run like a drunk, three-legged gypsy at a paired couples waltz!