looks like there were 3 diff swingarms for pre oif a65, for years 62-4, 65-8, 69-70, no details yet other than mounting part(s) diffs for 65-8 vs 69-70
https://www.draganfly.co.uk/index.php/bsa/bsa/a50-a-a65/1967/category/271-swinging-arm
https://www.draganfly.co.uk/index.php/bsa/bsa/a50-a-a65/1970/category/347-swinging-arm
i'm gonna focus on 67 cos thats what i have
i don't have many of those skills, or experience, in making a change, first thing most folks look for/at is what options & info is out there, having access to info allows easier decision making to then move forward with,
if you google xs650 swingarm swap, there is tons of available info, along with other makes & models vs practically diddly for a65,
ran across some stuff tho, an oif a65 deal
http://www.bikebound.com/2015/08/11/1972-bsa-thunderbolt-custom-hill-climber/
high end
http://www.malarkeyengineering.co.uk/bsa-a65
vs home brew
https://www.ebay.co.uk/itm/1969-BSA-Thunderbolt-A65-R7-413-swing-arm-extended/291049576678?hash=item43c3e818e6:g:hWYAAOxydlFSr111
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i'm looking for all dimensions like these
http://www.xs650.com/threads/swingarm-pivot.35933/#post-363215
xs650 - Pivot Tube:
ID - 16.02 mm - (0.631")
OD - 21.95 mm - (0.864")
norton mk3 spindle OD
https://www.oldbritts.com/13_100005.html
Swingarm Pivot Spindle, MK3, .8745" O.D.
a65 pre 69 "Spindle Diameter: 5/8" (16mm)"
https://www.feked.com/bsa-swinging-arm-spindle-solid-type.html
5/8" = 0.625
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some of the options for xs650
http://www.motolanna.com/ourshop/prod_2637748-Swingarm-Aluminum-Alloy-SuperLite.html
key point, the SR500 and XS650 swingarms have the same pivot dimensions
http://www.motolanna.com/ourshop/prod_448876-Swingarm-Aluminum-Alloy-SuperTuff.html
other stuff
https://www.ebay.com/itm/XS650-xs-650-75-84-swing-arm-under-brace-weld-on-kit-1-joe-wiseguy-/263209242491
https://www.ebay.com/itm/XS650-xs-650-75-80-84-drum-brake-swing-arm-powder-coated-braced-new-bushings-/263121267436
https://www.ebay.com/itm/XS650-xs-650-swing-arm-stretch-and-under-brace-weld-service-xs400-rd350-sr500-/391850435325
https://cognitomoto.com/products/xs650-weld-on-swing-arm-extenders
http://www.xs650.com/threads/b-1982-3-25-extended-swingarm-125-b.42154/
diy jig
http://xs650temp.proboards.com/post/29281/thread
it would be sweet, if a xs650 swingarm swap was doable via some cheap easy mod,
pretty sure the yam tx750 swingarm, bit bigger, beefier & longer is a direct bolt in for the 650 frame
some mods with a kz1100 conversion,
https://www.kzrider.com/forum/11-projects/599144-another-kz1100-cafe-streetfighter-build#684560
luv this guy, sez in the thread "This is the first engine I've ever worked on, so any tips would be very appreciated" lol