Dyno run

Discussion in 'Norton Commando Classic Motorcycles' started by Fullauto, Oct 23, 2017.

  1. Fullauto

    Fullauto VIP MEMBER

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    Apr 13, 2009
    Had the "Nortan 850" dyno'd last week with very interesting results.
    dyno run.jpg
    The engine is standard apart from a Fullauto Technologies head, a PW3 cam and a VM34 Mikuni. The rapid dip in the torque curve is interesting. The motor is very strong in the low end and mid range as you would imagine with 50 ft/lb of torque at just over 3000rpm. In fact it is a delightful engine to use. You tend to maintain very good momentum using quite moderate revs, which is what I like.
    The operator should have known how to spell as he worked for Mortlocks, the West Australian Norton distributors pre delivering Nortons in the 70's. Tell me what you think.
     
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  2. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    I reckon you’d have over 50 horses, with little or no detriment to torque, if you fitted twin carbs.
     
  3. Fullauto

    Fullauto VIP MEMBER

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    Yeah, but I generally don't go to the top end of town, I get 65mpg, and it is such a nice ride with that torque, which is what a Norton is all about I think.
     
  4. Onder

    Onder

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    May 11, 2010
    Imperial gallons or US gallons?
     
  5. Fullauto

    Fullauto VIP MEMBER

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    Apr 13, 2009
    Imperial.
     
  6. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Are you sure that your 2600 to 3400 rpm readings are sound? The graph looks very volatile, and I notice the line is dotted, is that to indicate that the data shown is not ‘sound’?

    I know that when I run on the dyno it is very difficult to get reliable readings below 3000 ish for some reason.
     
  7. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    This is a pic of a run I did when I first built mine (JS1 cam, JS 10.5:1 pistons, 35mm FCRs, stock RH10 head).

    You can see how my data wasn’t ‘clean’ below 3000rpm.

    But you can also see how flat the torque curve is. It’s close to 50 from 3400 and doesn’t drop off until after 6000. Hence my suggestion that good twin carbs would be good on yours Ken!

    BTW, the last run I did was 64.6 bhp (after Comnoz head work) but the dyno computer was unable to print out the torque graph, which is kinda annoying!

    14E272F1-A193-4D43-96A3-9909CD1B83BA.jpeg
     
  8. Fullauto

    Fullauto VIP MEMBER

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    Apr 13, 2009
    Yes, it's weird how the torque curve peaks and then drops away quickly. More changes coming, but it's a very satisfying ride. And I'm prepared to bet that you don't get 65mpg!
     
  9. Madnorton

    Madnorton

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    Jun 9, 2008
    Or the English gallon, long time since I have seen it used thank goodness, caused much confusion especially with the younger Submariners. Some did question what is an English gallon then, if the UK use an Imperial one. On occasion some assumed it was the same, usually to be briefed by the Commanding Officer in no uncertain terms, when the tankie explained that they have not had enough fuel delivered!

    I agree that dip is not nice sat there, right over where most of the throttle would be used for cruising. Get some amals and let them pour some fuel in that engine, things will improve, but mpg will drop. You don't get something for nothing.
     
  10. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    I reallly haven’t got a clue what my MPG is Ken.

    Can’t quite work out what, if anything, is below that on my priority list! I just don’t do the miles to make it an issue.

    BTW, I once calculated that my 840cc racing Triumph was doing 12mpg (whilst racing)! I’m pretty sure my Commando is a lot better than that...

    BTW # 2, whilst I agree with Don that slapping twin carbs on and getting more Dino juice in there will improve things, I personally do not think that the ‘peak and drop’ in Ken’s graph is real. My money is on it being that the dyno wasn’t reading or recording cleanly at that point.
     
    concours likes this.
  11. Fullauto

    Fullauto VIP MEMBER

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    Why would I buy Anals? I've got better things to do with my time than screw around with Eccentrics!
     
  12. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    You’re being harsh there Ken...

    Sure, there’s no way I’d consider swapping the FCRs on my Commando for Amals! But having recently fitted some new Premiers to my ‘68 Bonnie, I am impressed at how well they function (ably asssited, no doubt, by the Tri-Spark I also fitted).

    Nevertheless, you’ve got FCRs or CRs to choose from in ‘bolt on kit’ format.

    Jus’ sayin’...
     
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  13. Fullauto

    Fullauto VIP MEMBER

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    I've got a TM34 sitting right next to me that I've done initial jetting on. I will fit it shortly after I play with the VM a bit more.
     
  14. The Buckeye Rider

    The Buckeye Rider

    Joined:
    Jan 1, 2005
    Every one on this forum is eccentric and you spend plenty of time here!

    I have a stage I cam and 30 pistons over with a single Mikuni with a 21 tooth front sprocket and get 45 mpg (US)

    Ride On
    Dave
     
  15. Brooking 850

    Brooking 850 VIP MEMBER

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    Oct 3, 2011
    Hi Ken, I had similar sort of readings with my standard Roadster, it was a problem I carried over to my race motor when setting up and testing.
    Mine was due to the mufflers I was using robbed all the torque and power out of both engines in the mid range never mind what carb and timing settings I used.
    On my Roadster I have twin carbs with quite noisy peashooters , I get 50 + MPG riding it in a spirited manner on NZ roads .
    The power and the torque is back with the current muffler set up.
    Does you AF ratio run rich where the dip is on the P & T curves?
    Regards Mike
     
  16. 850commando

    850commando

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    Nov 1, 2014
    ok so you got my attention. i grew up with an imerial gallon and a us gal, never heard of a english gallon, its not even in the conversion tables... what is is in relation to litres....
     
  17. gortnipper

    gortnipper VIP MEMBER

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    Nov 11, 2013
    What mufflers on your Roadster? I have some new Commando Specialties peashooters, which I believe are Emgo. I would have liked your 2:1 setup for sure, but I had wanted to keel the pillion option, which I may not be so clear on now. But, then there is the $$$ thing which is getting short.
     
  18. CanukNortonNut

    CanukNortonNut

    Joined:
    Aug 8, 2005
    Nice dyno run Ken. You would get more hp with twin carbs.:D
    2012 on a trip to the east coast and back in the months of August/Sept. I got great mileage on my 850 with re-sleeved Amal mk1's on a 3000 mile trip. I ran a 21 tooth final and Maney belt drive. I calculated it out to get around 65 miles Imperial gal. Stock engine with electronic ignition
    I kept all the gas receipts and added it all up at the end of the trip. I had camping gear to weigh me down. This pic of that trip was part of one of the calendar a few years back. https://www.accessnorton.com/Norton...3-ready-for-download.13284/page-2#post-187549 ( ninth down).
    Amals are no slouch for mileage if set up correctly.

    Cheer,
    Thomas
     
  19. worntorn

    worntorn

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    Dec 22, 2006
    +1 on the twin Amal economy.
    I've recently gotten as high as 150 Chinese miles per Old English Ale gallon on twin Amals.
     
    concours likes this.
  20. Fullauto

    Fullauto VIP MEMBER

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    Apr 13, 2009
    Using a cider additive?
     

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