Yes. Well the newer one with the power upgrade has no problem. Can't speak for the earlier ones as I haven't ridden one.
I have had mine “cruising smoothly” at 120mph. At about 100mph you still have a bit more power at your disposal without being too high in fifth gear. With that said it still feels starved from the factory, and if you really need it to be down to fuck, check out my newest thread on getting the most out of the street twin.
I own one, last years model in fact, do you? If you need proof take a look at the manufacturer claimed top speed.
Triumph is now listing top speeds for their models? I have yet to locate any information on the official website to back your claims. Perhaps you would be kind enough to supply a link so this 120mph figure Triumph list for the Street Twin could be verified. The main problem here is that you are confusing Cruising Speed and Top speed. Top Speed is not Cruising Speed. It never has been, it never will be. Someone who once designed the odd Triumph engine here and there once said that for engine longevity initial running-in speed should be no more than 1/3 of top speed and cruising speed no more than 2/3rds of top speed. Whilst engine development has unquestionably changed since that conclusion was reached by an engineer you simply cannot cruise all day, every day, year in, year out on any vehicle created with anything more than a modicum of performance at its top speed and expect it to last for any length of time without component failure. A Street Twin is not cruising IF it's travelling at 120mph.
I mean, I thought it was fairly obvious I I was saying it was the top speed, like a haha yeah "cruising speed" type deal. That engine break in period myth has been debuffed, guy bought two brand new engines specs em out and rode one all day at the redline for 500 miles on one, and like a little fairy on the other, and found no remarkable difference. Anthough light, cautious use can prolong the life of any engine, modern ones are designed with rev limiters, fully synthetic oil, and liquid cooling to allow one to consistently use the top end of their engines performance. That’s what racing is, that’s what bikes have always been about until Harley started poisoning the older generation with dreams of cruising for I’ll gotten gains. I put a lot of stress on my bikes and I’m proud to say I maintain and service them in a way they keep preforming, I’m not looking for a bike that is so babied it is immortal, I’m looking to ride it to its limits. And I can tell you from experience the street twin can do 120 stock, and the bike is comfortable above 100mph, ones gentle sensibilities may not be, but the bike is DTF.
I would say yes but depends on conditions. Weather traffic and location. Major differences like UK v Utah. Rain or dry roads. Keep in mind the faster you go less likely you survive a crash.
I'm sure the engine can ride 80 mph (130km/h is our legal speed on motorway in France), at that speed without fairing it's more a rider durability question.