There will be a bearing code written on the side of the bearing, if in doubt, knock one out and take it with you to the bearing factors, they will know where to look...
I've just done the front bearings on my XC, and dont think i got much change out of £30 for bearings from a bmw dealer. Guess you might cut that in half from by going to a specialist..
Ask someone who has done the job already, or remove them and take a look on them for the number, or measure them and I can take a look in a catalogue for you.
In fact, if your in the sh!t with it, whip it down here and I do the job for you......... I'm not cheap though.
Hi Timpo, this is the number for the rear sprocket carrier, but the page in the faq of the chaingang which lists instructions and the part numbers is the link you see below.
Ginger, it is about time you learnt to use the fiche's on the net. Check http://www.realoem.com The description gives the size of the bearing and seals. you can then use the search option on simplybearings site to find and cost the bearings. They also do seals.
You will need circlip pliers and a heat gun to do the rear wheel's bearings. Also if you havent already done so get yourself the F650gs repair manual that is in pdf form and can be had at the f650 forum sites.