Just for my information
A 750 standard roadster beside an 850 standard roadster.
Which is the quickest say over a 1/4 mile both being standard and which has the best top speed?
Having owned both 750 and 850 Commandos , my '69 Fastback 750 was definitely more revvy and had the best top speed over both the Mk1a and Mk3 850's I've had. Don't know about a standing quarter mile but I'd guess the 750 would have the edge also. Can't remember what g/box sprocket there was on the 750 but both my 850's have 22 tooth.
Back in the early '70s with my 750 Fastback kitted out with clip-ons , r/sets and a 5 gall ally tank , recall coming back at a late hour from a NOC evening at the Oxford branch down a deserted M40 towards London and watching the speedo needle wobble between 120 and 125 mph for a short stretch. Don't do that anymore.
Good luck finding a 'standard' Commando :)
But, if you were to have taken standard 750 and 850 Roadsters out of the dealer showroom in 1973, carefully run-in for 500 miles, then the 750 would be faster over the quarter simply because of the gearing. The 750 would probably win out on top-end too, depending on the rider.
850s slowed down after '73 due to emissions rules affecting gearing, silencers and air box. Not difficult to make an 850 faster than any 750 though.
Bikes supplied to journalists by Norton were 'tweaked', so published speeds and times are suspect.
I read many years ago a road test between 750 and 850. Result was..... 750 quicker off the mark and top end. 850...... better manners and smoother torque delivery and better flexability.
A 750 commando fitted with a Dunstall 810 big bore kit was apparently a lot quicker than a standard 750. I wonder why a Mk1 828 would be slower? It's just an over bored 750 with bigger carbs.
The large bore improves flow around the inlet valve and so an 850 has the potential to be quite a bit faster. But a standard 850 Mk1 has lower compression, taller gearing and is a tad heavier so is marginally slower than a 750.