I'd been looking for luggage options for my bike (96 600F3) and tried a GIvi tank lock bag but found it restricted movement on the bike a bit.
I looked at various seat bags in stores but there was nothing I could find that wasn't going to damage the rear plastics.

I realised I still had a small Moto Fizz seat bag in the garage I'd bought a few years earlier that might do the job.
The Moto Fizz bags are made by Tanax, a Japanese company. We don't usually get them in Australia but I picked mine up from a guy that lived in Japan for a while and brought it back.
Mine is one of their smaller bags, the MFK-100. Its 370mm wide by 300mm long by 200mm high. It holds 17 litres but can expand to 570mm wide and hold 25 litres. Their largest seat bag holds a whopping 75 litres.
The bag comes with 4 straps that have a loop on one end and a male clip that adjusts along the strap. After some trial and error I looped the straps together in pairs and passed them under the seat front and rear- the bag doesn't move.
I highly recommend this bag if you want to avoid damaging your body work or fitting a rear rack. It's well put together and well thought out, very Japanese.



Beautiful afternoon for a ride and some whale watching from Royal National Park, Sydney Australia