Thanks for the quick reply, I haven't any photos, never even thought of taking any. There was maybe half a dozen bits, none bigger than a grain of sugar, only noticed them as they stood out against the thin layer of oil left at the bottom of the pan.

No discernible shape really. Would have thought they should have been caught by the filter or would they sit at the bottom of the crank case maybe?

Bike is running and sounding fine, could have sworn it's running smoother after the oil change but could be my imagination