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New 850 at Barber

Discussion in 'Norton Commando Motorcycles (Classic)' started by Fast Eddie, Apr 13, 2019.

  1. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    If 60 is wildly optimistic for crank hp, what is the correct bhp rating for an 850 Commando then?
    Also, what should the proper number be for a non Combat 750?


    Glen
     
    Last edited: Apr 13, 2019
  2. jbruney

    jbruney

    Joined:
    Jan 5, 2019
    I'm looking in the venerable old Haynes book I've held on to since Rome fell and it places the 850 @ 418-430 lbs. (190-196 kg.) dry weight*. When my speedometer worked well in her younger years I believe I coaxed about 110 out of it and backed it off over concerns of blowing up what probably couldn't, at the time, be fixed.
    That was fast enough anyway because there was the XLCR handy which had more wind....I would also give the silky a good home, but I'd make it scream like a spanked harlot...collector value be damned.
     
    Last edited: Apr 13, 2019
  3. Onder

    Onder

    Joined:
    May 11, 2010
    Glen, what does your's weigh?
     
    Last edited: Apr 14, 2019
  4. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    40rwhp or less is my own take on the most quoted figures I’ve seen.

    10% or 5bhp being the figure often quoted by some as the amount lost twixt crank and wheel (Dave Nourish said it was 5bhp on his engines, I’d guess that fairly representative to Commandos).

    So, a good 850 should be around 45bhp at the crank IF all of the above is correct.

    None of the above is very scientific however, more like hearsay. Certainly wouldn’t stand up in court !!
     
  5. tomspro

    tomspro VIP MEMBER

    Joined:
    Jan 25, 2014
    I'm guessing that a 25 tooth sprocket, strong tailwind, and slight downhill run coulda got you 115+.
    Add a bit of speedo error and 120 certainly possible. :)
     
  6. Danno

    Danno

    Joined:
    Feb 7, 2010
    Probably one of those that were found still in crates in Belgium.
     
  7. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Well, I’m gonna go against the grain here and say that I hope those bikes REMAIN at Barber and out of the hands of riders like us.

    There are thousands of ‘riders bikes’ out there, we don’t have a shortage.

    But there are very few ‘new’ ones around and, IMHO their real value (not $$) is their value to posterity and and a reference to restorers, etc.

    Without such bikes, future generations would have no real reference points.
     
    kerinorton and oldbeezer like this.
  8. frankdamp

    frankdamp

    Joined:
    Oct 7, 2005
    Agreed, Fast Eddie. It's great that there's one left in the world that's original and never used/abused. As far as weight goes, the prototypes (the only Commandos I ever rode!) were about 395 pounds. I'm calculating that from having ridden onto a weighbridge. At the time I weighed about 160 lb. (don't I wish!) and the bike had about 1/2 of tank of fuel.

    The prototypes had weird-looking gas tanks with only about 2 Imp. gal. capacity. They also had no center stand or side stand. To park, we had to find a wall or post to lean them against!

    I don't remember the scale readout, but it must have been about 560 lb.
     
  9. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    Clearly states it was found here in the States.
     
  10. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    So how did those bikes run high 12 and low 13 second quarter miles out of the box as stockers? (Pre MK11A 850)
    And same question could be asked of the 750s which ran roughly the same or slightly slower times ( Commando Gold Portfolio)
    Even with a 140 pound rider if it doesn't compute with 45 crank horsepower.
    Although 60 may be generous I believe 45 is below the stock output.
    The 750 version, non Combat, outran the 65 bhp rated Honda 750 4, same rider, same track, same day.

    Glen
     
    Last edited: Apr 14, 2019
  11. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I’d say it’s down to the Commandos torque being able to launch it off the line. I think that’s why the Commando is fast. Again, this is proven by folk (like you) who do ride them fast, but seldom rev to 6,500rpm, which would be needed to find the peak power. You’re going fast on the back of the torque curve, not the peak power.

    I’ve also spoken to Triumph owners who were disappointed their bikes were way below the 52bhp claimed. But, take off 10% due to manufacturing tolerances, then take off 5bhp for transmission losses, and you’ve a sub 40rwhp bike before anything is ‘wrong’ with it!

    Over on this thread we have two tuned 850s with Fullauto heads producing 46 and 48rwhp respectively and a closer to stock bike at 40rwhp: https://www.accessnorton.com/NortonCommando/dyno-run-2017.23986/page-14

    On top of that, I’m sure I’ve seen readouts of around 38rwhp on this forum but I can’t seem to find ‘em.
     
    Last edited: Apr 14, 2019
    Dommie Nator likes this.
  12. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I have a friend with a well running, never rebuilt (engine at least) mk3.

    It’s got the earlier air filter and peashooters, so should be a few rwhp up on stock. I’ll try and persuade him to come to the dyno with me one day.
     
  13. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    If the Commando 850 is only 45 at crank I hate to think what my 46 bhp factory rated BSA is producing !
    Agreed the best part of the Commando is low and mid torque. It's nothing special above 6 k, I don't even bother waiting around for it these days. Better to shift and go.

    We had quite a bit of discussion of the Duckworth dyno charts, 750 and 850, here some time ago.
    It was decided by at least one member (Rohan) that the dyno chart for the 850 had to be reversed as it had a big bump around the 3000 rpm point.
    Since then we have seen quite a number of 850 dyno charts with that big bump or sometimes a spike right there.
    The 750 doesn't seem to produce that.

    Glen
     
    Last edited: Apr 14, 2019
  14. Onder

    Onder

    Joined:
    May 11, 2010
    The other day I needed to get past a car and what with the small space and poor judgement I had to go past 6k in second and third.
    Everyone survived and I was rather surprised to find quite a bit of power up there and that it didnt tail off at all. So that you dont have
    to ask, Andover peashooters on single pipes, stock ham can filter, amal premiums, 260 mains, Fullauto head, Pazon Altair, TTI box and
    me weighing in at nine stone full kit. Rest of the bike is stock.
     
  15. jbruney

    jbruney

    Joined:
    Jan 5, 2019
    The sweet spot. I can always recognize a Commando by that sound when it catches it. 60 hp is selling hp. Bought hp is an entirely different matter it would appear. I still ride, maintain, & am captivated by one totally unencumbered by the knowledge of those facts. I really do enjoy the research into these matters of magic.
     
  16. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    9 stone...

    There’s performance tuning, right there !

    I was 9 stone once, but wudda been too young to ride a motorbike !!
     
  17. CanukNortonNut

    CanukNortonNut

    Joined:
    Aug 8, 2005
    Fast Eddie,
    Yes I realized that but what I had at my disposal was my shop manual for my 74 which gave the weights for the bike depending on the dress. While scrolling down the pictures that you graciously shared with us, I incorrectly assumed that the Barber sign was at the Mrk3 roadster.
    With that said, I know that the Mrk3 had hundreds of changes made in that year. Some of it I wondered if their decision to change, was a move forward. For instance, it would be interesting to find the weight of the earlier drum rear brake system as a total and the Disk system which they used for the rear wheel, in which they still used that big lump for a caliper and the same size disk? Larger Battery and the E-start assembly would give it more weight that I know but was the other mods just more window dressing?
    Cheers,
    Thomas
     
  18. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Stronger crankshaft
    Stronger crankcases
    Stronger frame and swing arm
    Transmission improvements
    Cush hub capable of cush

    All good window dressing

    Glen
     
    CanukNortonNut and Fast Eddie like this.
  19. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Glen, as one of the few who’s actually weighed their bike, can you remind us what yours tipped the scales at?
     
  20. 998cc

    998cc "Cheap" is rarely the least expensive. VIP MEMBER

    Joined:
    Oct 1, 2018
    And I thought it was a Flying Squirrel in the background. A 2-stroke 700 twin would be a touch lighter 'n a Commando! :D

    Cheers!
    ~998cc
     

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