Hi,
The final drive & wheel are unique to the 1300. no other model shares.
This means the only way to go 3 spoke is to cut the centre out of the 1300 wheel & somehow "graft" onto another rim & spokes.
You need to allow for the offset & alignment with front wheel too.......be careful !!!
There is someone in Germany who can take an original wheel & fit a wider rim, but spokes remain as stock. This German guy does a very good job & a few owners have used him.
Never seen a 3 spoke refitted to original 1300 centre yet.
I have a 3 spoke rear wheel on my current bike but that meant having a one off swinging arm made to accept a Yamaha VMAX final drive & a one off spindle kit to then fit a Yamaha XJ900 Diversion 3 spoke rear wheel (which accepts a 160 tyre).
The VMAX final drive is also upside down as its on the other side of the bike on a VMAX, but this does not create any problems. It also means a lot of work for rear suspension.
The 160 section wheel was wide enough for me as I dont want to radically change the appearance of the bike from stock, just update it to modern size tyres, brakes, suspension etc, & thats what I have done. It makes the bike 4 inches longer than stock too.
My front wheel is a 3 spoke from a Yamaha R6 which was quite easy to fit & using a digital speedo so no issues with speedo drive gearing.
The bike rides & handles much, much better than stock & much better than I expected it would. Very sharp & predictable on corners & the 4 pot calipers make it stop like any new bike. The rear caliper is 4 pot I adapted from a Yamaha FZR400RR.......and again is superb !
Hope that helps?
Pete F
UK