| I'm doing much the same thing myself but have a limited run 916 style item that is designed to fit the rear of an SS machine.
Monoposto - single seat, rider only
Biposto - two seat, rider + pillion - but if the pillion padding on my seat unit it anything to go by a pillion will need to have some built in padding!
Bear in mind you will probably loose the grab handle, not a big deal but I found it handy for moving the bike occassionally and you might loose easy access to the toolkit area under the pillion seat.
Sargeant make an SL type seat pad from memory but really yes you are right, replacement seat do seem to be fewer.
I have a reasonable collection building:
Standard Seat x2
Corbin Streetfighter
Custom 916 unit
Good luck ! |