You need a special flywheel pulley. I tried too, i even tried holding the magneto still while turning the bolt but didn't work. I did though just spot some flywheel pulleys on ebay yesterday, ill post the link up in a minute.
Cheers.
lol pully's
reminds me of this idea i had come up with to wrap a tie down around the flywheel and too the roof of the shed to try and get the flywheel off