The dual disc front hub will swap over, but the rear 640 hubs are too narrow and come with 20 mm bearing setup.
We would have parts to build a wheel for the rear 990.
The 950 and 990 hubs are the same, they used a wider disc side spacer on the 950 SE and all 990's.
Originally Posted by Alchemist
I have a 640A with a set of superrmoto wheels as well (17 inch f/r). Can you advise if its a straight swap to a 990R (potential purchase). I recognise your suggestion of 19inch front but wanted to know if the hubs etc(Talon) will fit. I'm pretty positive about the front since its the twin disk model which I understand is identical to 990 but not sure about the rear. Can I just run it backwards (ie dissk on other side) ? Too much trouble, do I just ditch them and start new, is weight difference a worry ? Any help greatly appreciated