Splitting crank is actually a lot more difficult on that motor as it has a steel plate on left side to direct oil from main bearing to big end. Earlier bikes (CB350 et.al.) had a 'lip' on flywheel so caught oil centrifuged out of main bearings to lubricate big ends. (they are not pressure fed) The 125 version of the motor had left side big end failures if oil was not checked regularly and kept between middle and top mark of dipstick. (125 also has a 12,500rpm redline) I have changed left big end bearings on 125 but it isn't easy. Freezing the crank and applying local heat to outside of flywheel may enable the plate to be removed without damage but it's a difficult crank to fix.
If you want to split cases, just make a tool from some flat plate and a few nuts and bolts. If it isn't coming apart relatively easily you either still have some bolts in place or your using tool wrong.