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Commando Top Speed? (2010)

Discussion in 'Norton Commando Motorcycles (Classic)' started by highdesert, Dec 21, 2010.

  1. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Rohan,
    When I first raced the bike a few years ago, it was fitted with the standard box. It was revolting to ride, impossible to change down without a heap of revs, really difficult to be smooth. Then I bought a 4 speed CR box from the US. First gear was higher than a manx 1st. Getting the gearing right for most of the circuit meant that first was too high for the clutch starts. Most of my race starts were too slow. I've now bought a TTI 6 speed box with the first gear half way between standard commando and manx ratio. Because of my usual battle with the chains, sprockets and adjustment, I inadvertently used one tooth too high on the engine sprocket and the gearbox sprocket as well. The motor struggled to get the bike mobile, but as soon as it got rolling, it took off in a flash. I think the 6 speeder will be excellent, but I'm not looking forward to the next fight with the chains. I'm using single row chains, and I'm trying to avoid half links. It is the same old story, everything is either too big or too small. I end up with the wheel too far back or run out of adjustment on the gearbox. I can afford to end up with the overall gearing slighly higher than it has been, but even going up by one tooth presents problems. It's just one of those things with old British bikes - they are designed to drive you insane. But I can't really blame the British - I built the bike myself, when I was much younger and things were simpler.
     
  2. pommie john

    pommie john

    Joined:
    Nov 18, 2005


    That article describes how horsepower is turned into heat, not how horsepower is measured on a dyno from the heat.

    How would you measure the HP output from measuring the temperature of the water in the brake? It changes far too slowly for it to measure the engine's output over rapidly changing rpm.

    The water brake dyno that I used measured torque simply by having the brake mounted at the crankshaft end, and the brake was stopped from rotating by an hydraulic cylinder. As the brake tries to turn with the crankshaft, it pushes against the piston of the hydraulic cylinder, but unlike a clutch or disc brake, there is no slave cylinder, just a reservoir that gets pressurised as the piston is pushed by the brake. Torque is proportional to the pressure in the hydraulic system, and horspower is calculated from that.
     
  3. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    The link is from the dyno manufacturer, if you read the entire article, they explain quite clearly how their water brake measures heat.

    There are many types of dynamometers, some measure torque, this type measures horsepower as explained in the article.

    Glen
     
  4. pommie john

    pommie john

    Joined:
    Nov 18, 2005

    I don't see that bit. maybe you could highlight it for me? There's a part that says:

    "The wider the valve is opened, the more water it allows to flow to the dynamometer. This flow to the dyno is directly proportional to the amount of horsepower being absorbed."

    But that's water flow, not temperature measurement. There's plenty of talk about the equivalent of horsepower and heat, but I read that as a discussion of making sure the dyno has enough capacity to deal with a given engine's output rather than as a way of measuring it.
     
  5. JimC

    JimC

    Joined:
    Oct 12, 2007
    It's my understanding that measuring the water temperature of a dyno could determine horsepower if used where a constant rpm motor is being tested, such as an electric motor. It's true, heat is a measurement of power, but as was pointed out by John it would not be suitable to determine the horsepower of say, a Norton.
     
  6. hobot

    hobot

    Joined:
    Oct 19, 2005
    HP could be determined by the speed of heating a measured amount of water up some many degree's but that be rather crude over the time scales involved and the losses through container and pipes. One hp = 745 watts heating work.
     
  7. 1up3down

    1up3down

    Joined:
    Jan 12, 2011
    Seems most stock Commandos have in the neighborhood of 45 rear wheel horsepower

    if I remember Jim Comnuz saying from his dyno tests
     
  8. JimC

    JimC

    Joined:
    Oct 12, 2007
    I think you are referring to Jim Comstock, who's login handle is: comnoz. I also think you have horsepower and torque confused.
     
  9. worntorn

    worntorn

    Joined:
    Dec 22, 2006

    Here is alink that gives a short explanation of how a water brake measures heat rise of the water to give hp. Third paragraph down-
    http://www.allpar.com/eek/hp-vs-torque.html

    I think some of the confusion may come from the use of hydraulic dynamometers which are sometimes mistakenly called Water Brakes. Hydraulic dynos measure hp via torque.

    And here is another make of Water Brake. Note this one offers three methods of measurement. Measurement type 2, measuring water flow and delta T is the way our(Murray's) old Dyno works. Its not fancy, but it gets the job done!
    http://www.hydra-brake.com/default.asp?page=operate

    We have in the Vincent Club the original Water Brake from the Vincent Test House at Stevenage. The highest horsepower ever recorded on it was from a Supercharged 1000cc twin running on gasoline. It recorded 119 horsepower, the year was 1956.
     
  10. J.A.W.

    J.A.W.

    Joined:
    Jun 6, 2012
  11. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    They didnt test the mighty 828. It has 8 extra foot pounds over the 750 commando. Add 8 to 43.88, you get 52.88 which will crush your smokey tankslapper Kawasaki.
    Ok maybe not crush, but it is more...ish.


    Glen
     
  12. J.A.W.

    J.A.W.

    Joined:
    Jun 6, 2012
    Over the FULL 3000+ rpm power- band?, If so, I want one...
     
  13. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    We all want one.....oh wait, I already have one.
    Ok I want another one :)

    Glen
     
  14. J.A.W.

    J.A.W.

    Joined:
    Jun 6, 2012
  15. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Never warmed to the look of them, sorry. But if it is all you've got, by all means ride it, just make sure you get her slowed down to nothing before the corner comes up..... :)

    Glen
     
  16. J.A.W.

    J.A.W.

    Joined:
    Jun 6, 2012
    Funny/ironic, that whole quote used to be applied to Vincents too..
    Mind you, like Vincent with their double front brake, Kawasaki offered a 2nd front disc as a dealer option , from new..
     
  17. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Sorry, Im in the wrong forum, Im looking for the Norton Commando Forum, must have gotten transferred here to the Kawasicki forum by mistake. :)

    Glen
     
  18. J.A.W.

    J.A.W.

    Joined:
    Jun 6, 2012
    Were you looking for the Egli-Vincent forum?, How difficult is it to apply those 850 speed-tuning factors to an 850 Mk 111?
    Is it the one to pick, even if a bit of a lazy porker when new?
     
  19. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Definitely!
     
  20. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
    Funny thing , it wasnt a lot more expensive to buy a second H2 , than a 2nd disc FOR your H2 , and made more sense , if thats possible with a Kawaski . :p
     

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