I can't push my '81 Sportster past about 90 mph without the front end trying to do its own thing, even with tapered neck bearings. About 105 mph or so is as far as I've had it. Though it's capable of more, it just aint safe. I didn't set it up for that kind of speed anyway.
But it's an '81 Sportster with numb-handed bar position.
Actually: .. But it's an '81 Sportster.. is all that needed to be said.