Take the bearings to a bearing supply house to match up, but do not be surprised if they are proprietary sizes and only available from Yamaha.
The codes c2,c3,c4 are different internal clearance specs. to allow for different rates of expansion of the inner and outer race.
If there is no c# number then they are standard clearance.
A bearing with more clearance than standard is safer to use if you do not know which is correct, so I would use c3 (more than standard clearance than standard) if I could not find out the full and exact spec.