So, I need to change the big end bearing, because there is up and down play. I understand that this is a difficult thing, and I need to bring the motorcycle to a motorcycle service. My question is: what do I need to buy? I buy a new big end bearing and that's all? Or I need also a new crank case gasket, head gasket? And what else?

Another question: my engine is split now. Do I need to bring the whole engine to the motorcycle service? Or can I get out somehow the crank shaft (or whatever) and bring only this part to the service? If yes, then how can I get out the crank shaft?

Beta do a conrod kit that comes with rod+ big end bearing & pin + thrust washers all for about 100 quid! take your main bearings to a bearing shop and get them matched up as beta ones aint cheap! and get crank seals +full gasket kit from beta!