my $0.02 worth on instability
This is a little late, but what was the last thing you did before the instability issue began? My story: I always ran Metzeler 77's but there came a time in the mid-90's when they were hard to find. I installed Cheng Shin 906 & 907 tires at the recommendation of a cheapskate friend who ran them on his Earles fork BMW with no problem. I installed them and got immediate weaves and instability over about 45 mph. At the recommendation of other /2 owners, I cleaned/inspected/lubed/adjusted the front and rear swingarm and wheel bearings, as well as the tapered steering head bearings; went thru the friction damper to make sure it was right; replaced the front and rear suspension dampers; and did everything short of killing a sacrificial animal and sprinkling its blood on the bike. Finally I remembered the first lesson of Troubleshooting 101, and I asked myself, "What was the last thing I did before the problem started?" So I replaced the Cheng Shins with Bridgestone Battlax tires, and the problem was solved. I have never re-installed the Cheng Shins, and the problem has never recurred. I have run Bridgestones, Metzelers, and a mix of both with no problems.