Jap model 0 - how to split the crankcase

I have a Jap model 0 and I am trying to split the crankcase so I can get to the big end bearing. I have tried all ways to get the flywheel off without success so I am attacking the problem from the shaft side. There is what appears to be a plastic bearing cover which I assume needs to be removed but how can I do this without damaging it? Is it even possible to split the crankcase from this side or am I heading the wrong way completely. Any help would be welcome as this is a nice little engine and will make a great showpiece when finished but is being very stubborn.