What bike got you into this?

[gn2]

Both the 500cc and the 550cc were 4s.

There was a 500 twin in the 70s, CB500T, I had one.
https://www.bike-urious.com/1976-honda-cb500t/

[you you]

my first bike was a honda TL125......my first 'legal' uk road bike was a Suzuki TS0ER....my dream bike was / is a Honda 250N Super Dream deluxe

Is that the Euro styled late 70s one?

[Mel46]

Both the 500cc and the 550cc were 4s.

There was a 500 twin in the 70s, CB500T, I had one.
https://www.bike-urious.com/1976-honda-cb500t/

It is somewhat obvious that the CB500T was not popular. It was only produced for a couple of years. Compare that to the "4" and you can readily see that it had some problems. The vibrations at 50 mph were enough to make previous Honda riders wonder if they really have a Honda.