thanks for the advice pal but unfortunately this type of rotor is not the type with a thread so a normal Yamaha puller wont fit. I have now managed to free it with a little brute force, actually a sharp tap from behind. Its now all stripped and cleaned ready for the crank rebuild. One bearing was shot and the oil seal not much better, but still you wouldn't be a biker if you didn't like to do a bit of maintenance now and then.