I realise it's a 2 stroke Joe. The difference that makes is that the lubrication isn't really good enough to get enough oil into the big end at high speed for a journal bearing to work well, so the antifriction bearings are a good idea. On the positive side, the crankcase induction keeps the inside of the crankcase much cleaner than on a splash-lubricated 4 stroke, and that makes the antifriction bearings quite durable. Many 4 stroke motorcycles have fairly successfully used antifriction big end bearings, but they have dry sump pressure lubrication and a full flow oil filter, which keeps things fairly clean in there.
