Aye niblue,
May see you about, live in Perthshire and come into Auld Reekie now and again.
http://www.yuasa-battery.co.uk/motorcycles/motorcyclebatteries.html Try this if you've a while to spare, it's no very friendly, but the Yuasa site. I've just spent a wee while wrestling with it and went in via the battery type, tother way via machine type is

.
Yuasa battery for GB500 89-90 = YB12A-B (Not anything else in the Yuasa range!)
We are running an SRX600 and Honda Bros400 on Avon Roadriders and after Metzelers, Pirellis (one and the same, delaminating and through to nowt in 4K

) they grip and wear well.
I'd re-enforce SteveC#222 comments about getting a chain oiler of some description fitted. I've used Scottoilers and their oil, also chainsaw chain oil and EP90 with a touch of ACF50 in it [the latter two NOT being applied by the oiler, but a toothbrush to the inside of the chain after washing down].
Also elsewhere on this site there is a 'topic' about Motad prepared to manufacture XBR exhausts providing they get at least 10 requests for a batch. Several members have wrung or Emailed Motad, but not owning an XBR means I haven't kept an eye on progress.
Enjoy bopping about and go safe.
My regards, Bill.