zlrider,
After owning several bikes (6 to be exact) over the years, I have run across your situation a few times. If you eliminate the tire as a probable cause, it could be a few things.
Like many have already said, your head bearings are probably worn out. If I'm not mistaken, that bike weighs close to 800 pounds. It's not unusual to have the bearings wear out after that many miles, especially if the retaining nut was not torqued properly from the get go. Moreover, if you're a "heavy" front brake guy (like most are) this adds to the demise of the bearings.
or...
On my Ducati SS, I encountered some high speed wobble on the track one afternoon and the culprit turned out to be a cracked weld where the top tube connects to the head tube. Check very carefully the same welds on yours and make SURE that has not happened. There is nothing, I mean nothing, more frightening than realizing you were just going 165 mph+ on a race track and your entire front end could have just completely fallen off the bike!
I had a "dad" moment on the track one day after someone tried to pass me on the inside of a corner. He caught a pinch of grass, slid the rear end out, hot tire "caught" the asphalt abruptly stopping his rear end from sliding, he "high sided" the bike, went over the bars into the trees and received a helicopter ride to the hospital.
I proceeded to sell my last bike.
My past "collection"-
-1974 Norton Commando
-1984 Yamaha FJ100
-1985 Yamaha FJ100 with a 1380cc big bore kit
-1985 Yamaha RZ350 Kenny Roberts Special 2- stroker
-1988 Honda Hurricane 600
-1998 Ducati 900 SS SP (one bad mo fo!)
I still ride when I get a chance to ride a friends for a day, but with all the extra-curricular crap people do while driving their cars now, I'll pass on owning another one.
Now, where's that snow at....My sled is looking at me.
-J-
