Something that has not been mentioned here, and it's very important, is the body weight of the rider.
Proof of what I'm saying, is the statement that the wobble goes away when you add a passenger.
My friend Sandy spent pornographic amounts of money trying to get rid of the wobble. he even sent his frame to this company in Tennessee, that charged him over U$600, to put his frame on a jig, to check for any slight misalignment.
He got the frame back, re assembled the bike, and went for a "Spirited" ride, (I was following him on my max)
As soon as he got close to 120mph, his bike begun to shake violently, I thought he was going to wreck and take me out too.
Well he called this place in Tennessee, and explained the 120mph wobble, they told him he shouldn't ride that fast (LOL).
Now, Sandy is about 140 lbs, wet, and with a brick on each pocket.
One day, after listening to the wobble story one more time, I suggested to let me ride his bike on our way back from PA.
Well, I beat the "caca" out of that bike, went to 140mph several times, chopped the gas al high speed, and accelerated again,
and NOTHING happened !!! the bike was smooth as silk at high speed.
It is also worth noticing that, while I was riding his bike, he was following riding mine, and he never experienced any wobble with my bike.
The moral of the story here is:
Sandy is about 140 lbs wet, and I'm about 200 lbs dry
Sandy has original handlebars, I have the Superbike bent on mine (lower)
Obviously, seems to me, the lack of body weight, and upper body strength, is one of the main culprits
The original bent of the stock handlebars is no help either.
Sandy never could get rid of the wobble, and ended up selling the bike.
He bought a supercharged Vmax, that never wobbled, because it never ran properly.
Now that we are both old, he rides a motor scooter around town, and I'm still in love with my Vmax
Life is good