OK i need a 916 sp gudgion pin they are 21mm just to be differant from the rest at 20mm 
part number 12110221A and discontinued …bum!
Sounds like a job for an engineering firm. Or, fingers crossed someone can come up with an interchangeable part either way it’s a pain when bits are no longer available.
Put one Santas list he’s bound to find one for you! 
In the past I’ve used shortened XS650 Yamaha pins in my old Bevel twins Cosworth pistons, I’m sure that if you have a look around you’ll find something that can be modified.
I did swap* a pair of 916SP pistons to a mate Tim who wanted only one of them for his “JABSA”, a BSA pre unit single with a Jawa 4 valve speedway top end sprinter.
That was featured on the Carol Nash calendar one year, but I haven’t seen him for a couple of years now.
I could try and get in touch with him to see if he’ll sell his spare pin or piston/pin?
Or send me the dimensions of the pin and I’ll ask around, I’ve a few priceless contacts for this sort of thing. 
*I swapped my pair of used 916SP pistons for a NOS 851Tricolore Kit 888 barrel, piston, rings, all the shims, gaskets, cir clips etc.
I then used the barrel, rings etc in my tuned 916cc 851 motor and sold on the kit piston to a German 851Tricolore Kit owner.
Steve R
I have an old! xs650 in the shed.
i37.photobucket.com/albums/e52/g … CF2542.jpg
Dont think im going to pull it appart just yet though it took too long putting it together.
That’s a nice flat track XS, down 'ere in Cornwall one of my mate’s is building something similar and another has an XS motor in a Honda MotoX rolling chassis.
The XS pins are actually 20mm, my point was that all you really need are a pair of 21mm pins that you could then quite easily modify to your needs.
Early 750 roundcase Bevels used 21mm pins and they’re still available.
Steve R
21mm od
60mm long
11.95mm id *but
tapers from 14.7mm
Have a man looking and have called around 20 ducati dealers with no luck. 
I keep looking at the old one but it has just too much corrosion.
Found a pair of pistons rings and pins for £100