This really seems like the same thread you started in Motorcycle Safety on "Interstate Riding"...so , one thread, one subject. (not sure how it concerns safety BTW)
But a stock Vulcan will easily go 120 mph. But yeah if you are going into a stiff wind with a big windscreen , it ain't going to happen very fast.
If you want a bike that can pass folks quickly (that are already doing 80) while going into a stiff headwind, you do have the wrong bike.
If you say "she's only a 750" again , I may come down there and slap you...
It ain't the size of the engine , there are 500cc bikes that will run circles around the Vulcan 750. The bike was not produced with "performance" in mind. Most "cruisers" suffer this fate. V-twins in particular are not high reving motors, most of the power and torque come in down low, which is what most folks like in a bike like this...so that is how they make them.
Now you added a big windscreen to a bike that already was about as aerodynamic as a garage door, and you want to cut through the wind like butter? You'll need at least another 60hp. (And even with bigger jets , air cleaners and exhaust, you be lucky to add 10 hp.)
And with those performance add ons , you still will never see 130mph unless you run the bike past redline. (top speed on any bike is fixed, unless you change gearing)
So, if you want to pass cars like they are sitting still, take the 'vette. Or do like I did an buy a FAST bike. My FJR has a 1300 cc inline four that puts out 140hp. The fairing is ALOT more aerodynamic than any naked ride. The bike will go 0-60 in 2.9 seconds and I have yet to top it out, but have gotten up to 137mph...that with luggage and my wife on the back.......
My advice here is don't try passing cars like you are on a race bike when you are not. The Vulcan 750 is a very able bike that can do alot of things
bikes of its type can not do, but asking to to outperform it's on limitaitions is silly.
With that skinny front tire, it's poor aerodynamics, and the sometimes useless rear drum , I would not wish to go much faster than the bike is capable of doing. If you truely want to cut through the wind with that big windscreen on there, don't waste money on the engine mods, buy a bigger and "sleeker" bike.
KM