Motorcycle Repair: 92 Honda Nighthawk 750 rear wheel bearings, rear wheel bearings, honda nighthawk 750

Question
I have a 92 Honda Nighthawk 750 with 26000 miles on it.  I just recently bought it and had to replace the rear tire.  When I took the wheel off, I noticed that the bearings on the driven flange were totally shot.  Being so, I bought a new rear wheel bearing kit and had a shop put the tire and the bearings on for me.  I only drove the bike a few miles, and the bearings on the flange were shot again.  I had them put another new bearing on and had them look to see what the problem was.  They couldn't see that anything was bent or out of order, and I looked at it as well and everything seemed fine.  I took the bike out again and drove it about 10 miles and noticed that the bearing was going out again; some funny grinding was felt at my feet.  I was wondering if you may have some insight as to what's wrong, I am stumped as well as the mechanic who has it right now.

Answer
Hi Matthew.
 In thinking about your problem, there are only a few things that I can think of and here they are:

1)  Some other part could be worn down and oscillating, causing the bearings to wear.

2)  Lubrication issues relating to attatched components.

3)  Damaged or broken parts that have not, as yet, been noticed or inspected which are directly related to the final drive, causing excessive wear.

Other than that, I cannot think of anything that could cause bearing wear like you are describing.

Good luck.
FALCON