I would avoid aftermarket bearing/seal kits for this motor.
Here's a diagram with part numbers, if you don't have it already:
http://www.westernhillshondayamaha.com/ ... 25M-JPN-A/You should be able to get the seals, gaskets, and ball bearings from either Honda or eBay.
The 91014-360-006 / 91106-KC6-003 15x22x12 needle bearing (LH mainshaft) is an IKO TA1512 / TA1512Z, and may sub to a JHB HK152212. OEM Honda bearings are getting hard to find.
91016-360-006 / 91016-444-004 15x23x12 needle bearing (RH countershaft) - the NTN NK15/12 is a nearly exact sub for the OEM IKO bearing and is currently available on eBay, and I believe the HK152312 bearing is usable as well.
Ray