Join Date: Aug 2009
Location: Washington, the state
There are three bearings on the rear, two wheel bearings and one sprocket carrier bearing. Any one or more could be a problem. The rubber cushion drive dampers might be worn. Or crud somewhere it shouldn't be. Or the chain and sprockets. Or the chain alignment--don't trust the swingarm marks and sight down the chain for straight running. The chain and sprockets are the most likely culprits at this mileage, but it could be anything. Try removing the rear wheel, see that everything is clean, dry, fits right, and the bearings rotate with no visible rust, no noise, no notchiness--perfectly smoothly. The slightest defect is a bearing will only get worse. Let us know what you find.
"Older people who are reasonable, good-tempered, and gracious will bear aging well. Those who are mean-spirited and irritable will be unhappy at every period of their lives.
"Let each of use properly whatever strengths he has and strive to use them well. If he does this, he will never find himself lacking."
Marcus Tullius Cicero