750 vs 850. . . What's the difference?

Bonwit · Aug 2, 2009

Besides the obvious, what's the difference between a 750 and an 850? Did the the evolution to the 850 see improvements in the design and build of the engine? In other words, might one expect an 850 to be stronger? More reliable? Is there an appreciable weight difference? Do the two bikes handle about the same?

I've read here and elsewhere that the 750 has more pull off the start. This seem non-intuitive. Why is this?

Hope these don't come across as stupid questions. Inquiring minds want to know.

Thanks

bigstu · Aug 3, 2009

The 750 produces it's max torque at slightly higer revs.
So the 750 is a bit quicker off the mark than the 850.
The mk3 was heavier so this made the mk3 slower still.
The 850 has a bit more torque lower down so pulls well, giving the rider a feeling of a more relaxed accelleration curve.
Stu

batrider · Aug 3, 2009

No two Nortons feel or ride the same so it is hard to make a strict rule on this.

maylar · Aug 3, 2009

In very general terms..

The Commando evolved continuously from it's beginning to end. Every subsequent year had improvements over the previous models. The 850 engine has thru-bolts attaching the cylinders and lower compression than 750's making them more reliable. Other changes in swingarm, centerstand and steering head make the 850 more robust.

The 850 has a broader power band but the 750 has better kick-in-the-pants when it comes on the cam. Both are a whole lot of fun to ride.

Cookie · Aug 3, 2009

Plus the last 850s had an embroyo electric starter that can be made to actually work. Friends have told me the 850 is a better cruiser but i've never owned one.

Fullauto · Aug 3, 2009

750s are quicker off the mark because of their lower gearing, 19 tooth front versus a 21t on the 850s and 22t on the MK111s. I run a 23t on my '73 MK1 850 and love the easy 70mph cruising, with more than enough stomp for me in 4th gear.

ILLF8ED · Aug 3, 2009

I believe a lot of we 750 owners have changed to a 21T counter sprocket already, so that really doesn't fit as a differentiator. Geared the same the 750 excellerates faster mainly due to a higher performance engine - higher compression. Performance or relative relaxed power, it's a choice to be made. If any doubt own one each.

MarshalNorton · Aug 4, 2009

Do you like to just cruise? The 1974 850 is the answer, want raise some cain get a 750 combat :wink:

Vulin · Aug 4, 2009

does the 850 have more potential? I would assume if you tossed in some high comp pistons, cam work it would be quite a quick bike.

BillT · Aug 4, 2009

Vulin said:
does the 850 have more potential? I would assume if you tossed in some high comp pistons, cam work it would be quite a quick bike.

The only limitations are the wallet!

My 850 is stock - std pistons, original cam, 932s - and is pretty competent.

When I want a little more oomph, I ride my Triumph - also stock and essentially the same weight, more than double the horsepower.

plj850 · Aug 5, 2009

MarshalNorton said:
Do you like to just cruise? The 1974 850 is the answer, want raise some cain get a 750 combat :wink:

I chose an 850 as many reliability design issues had been sorted by the time it came out (1973) IMHO.

Ron L · Aug 6, 2009

I would assume if you tossed in some high comp pistons, cam work it would be quite a quick bike.

Mill 0.060 off the head, do a big valve conversion and a little port work, add lightened rockers, titanium retainers, a 2S or PW3 or Megacycle 560 cam, and feed it with a pair of 34 Mikuni's, Mk II Amals, or 35 Keihin pumpers. That will wake up an 850 :wink: :!:

bigstu · Aug 6, 2009

I have a 850 with a boyer and a primary belt drive but otherwise stock.
I went out two up with a mate two up on an exup1000 last weekend. Of course he was quicker, but I wasn't embarressed!
It revs to 6250 and goes pretty dam good.

I also went for a gentle run last night, cruising around the moors in Yorkshire (we even popped into Lancashire).
The Norton acted like a Harley, pulling from 1500 revs in third so comfortably. It was an absolute joy to ride.
Thats the thing about the Commando, it cruises like a Harley but comes on the cam just where the Harley gives up the ghost...

If your thing is out and out performance, there are many bikes out there to beat it. Its the combination of performance, cruising ability, torque and style that makes the Norton Commando one of the coolest bikes to have. (In my opinion)!
I think the 850 just edges the 750 in the 'all round' stakes.

Cookie · Aug 6, 2009

I think one of the joys of Nortons is that the Commando in either form is a truly ridable antique bike. Unlike my featherbed it does not pound you and you can find a truly smooth cruising speed.
It can be made quite reliable and will generally keep up with most other bikes on a run. I wouldn't challenge modern sport bikes all out but at legal speeds and a bit above the commando will do the job.
With this package you get one of the generally accepted beautiful bikes with those lovely peashooters.

swooshdave · Aug 6, 2009

bigstu said:
The Norton acted like a Harley, pulling from 1500 revs in third so comfortably.

You might want to get your Norton fixed. Or at least console it after you insulted it by comparing it to a Harley. :mrgreen: