Motorcycle Repair: Rear Brakes on 85, V65 locking up., rear caliper, vehicle mechanic

Question
Replaced and flushed all the fluid and put in new DOT4 as per my shop manual. Replace the rear pads with Honda's part and checked the rear caliper, not sticking. Removed the rear master cylinder and put in new kit, seals, piston and return spring. All worked o.k. for a couple weeks and then she locked up again. I did notice that there was only one hole from the reservoir into the master cylinder to provide fluid and return. There was another indentation for what seemed another hole but short of drilling it out it didn't seem like it was ever open. My Ford training, I'm a vehicle mechanic with an major utility, says that master cylinders for Ford cars have two holes leading into the master cylinder. I guess my question is, are there two holes in the rear master cylinder on V65's leading into the master cylinder bore, one larger and one smaller???? This bike has been a kick to ride over the years but this issue has me perplexed????

Answer
Jim,  You are correct that master cylinders need the second bleed hole to relieve the pressure in order for the caliper to relax its grip on the disc. The bleed hole is very tiny, but needs to be there to do its job.

A second concern is that it appears that you didn't disassemble the caliper and clean out the seal ring groove. This is the major cause of caliper sticking in old Hondas. Moisture builds up in the system, falls to the lowest point (caliper) gets under the seal ring and corrodes the caliper body, which expands the seal up against the piston.

Bill Silver