Previous posts are good information. I changed the main bearings on a Sherco and it was very straight forward. Probably two hours to strip, four or five hours to rebuild, back in frame ready to go.
One point I would make is take this as an opportunity to strip and inspect condition of all bearings, seals, piston, rings etc. There is really no point in trying to save time on not disassembling the full motor.
Best of luck - next time will be easier!