R6 Power problem

Hi guys got a problem with my 2001 R6. Full description of problem, i was riding on an A road and i was in fifth, tried accelerating but had no power, so i droppped it third, slowly pulled away. At the end of the A road there was a roundabout, i dropped to third but still no power, so i droppped it to first and the engine cut out. It runs fine with a battery pack, but as soon as you try to pull away it cuts out. I tried basic stuff like filters etc, but still no joy. My mate has a kawasaki and had similair problem, found out it was his side stand switch needed cleaning. Any help would be greatly appreciated as iv just bought a house and cant afford to send it to the garage. Cheers