Going to how fast a Vincent can be - back in the 70's I had a friend, Greg Duvall, who bought/tuned a Norvin built by Dave Furst (First?) here in Los Angeles. Gorgeous bike, built to be fast - twin Lightning heads, Amal GPs with remote float with megaphones, IIRC. British racing green, Cerianis, and a Munch Mammoth 4 shoe brake. We had a standing Sunday morning race than ran up the hill in Griffith Park and Greg always out accelerated everything - Nortons, Tridents, 750 Hondas, 500 Kawis. Then one morning, this is first half of the '70's, a local two stroke tuner and Park rider, Gary Schumake, showed up on his new 750 Kawasaki with chambers he'd built for it. Ooooh, the race was on. To get a good view, I made sure that I got off in third place on my Commando. Coming out of those uphill corners, that Vincent just killed the Kawi, AND it's wide ratios and wide power band maintained the murder right through to the end of the straights. Only later that day, when our Sunday ride got out of the Park and onto the long straight line national forest roads at well over 100 would the Kawi's close ratio peakiness close on that Vincent, but by then we were all running out of ratio. Great sounds that day. Greg sold that Norvin to AMA superbike builder/master machinist Tom Farrell; Tom had plans for it but it sat in his shop for years; I lost touch and Tom and that bike disappeared. If I could get it today, I'd trade all my bikes and cars for it.