A proper splitter and a press will get anything off. I broke a puller trying to get a timing sprocket off (and tore up a tooth on the sprocket). Took it to the shop where they have a press. Bink. Came right off with no fuss. Pushing is better than pulling...
But yes, that means taking the crank out of the motor.
1974 R90/6 motor w/1050 kit; twin plugged; installed in...1970 R60/5 frame; RM125 front end; KZ1000 Police Tank.