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Dyno run

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

  1. Fullauto

    Fullauto VIP MEMBER

    Joined:
    Apr 13, 2009
    Richness at the top and leanness low down. Once I've optimised the VM, I've got a TM Flatslide here ready to go. I've jetted it using the search function here to get a good start point using the knowledge of the good gentlemen on this site and then I'll optimise it. Then, I'll know where I'm at before trying twin carbs. I haven't quite decided which way to go there. I like the Keihin CR Smoothbores and I think the Keihin Flatslides are a little over the top, but, we shall see. Dyno runs will be regular.
     
  2. Fullauto

    Fullauto VIP MEMBER

    Joined:
    Apr 13, 2009
    dyno run 2.jpg

    hould have included this early on. It's the fuel/air ratio. Lean up to 3500 or so, then rich. Explains why I get 65mpg regularly around town and not quite as much on the highway.
     
  3. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Sounds like a good plan Ken. Please do keep us drip fed, it’s great to see someone being objective about these things.

    I would agree that you are weaker than I’d like to be under 3500, but it’s not massively weak when you consider that ‘correct’ Stoichiometric efficiency is 14.7:1.

    Still, it’s weaker than I’d like to be and as that’s where you spend a lot of time, you must be running hotter when at those refs than you otherwise would. I would definitely enrichen it a little there.

    As to the richness higher up, it will be interesting to see if weaknening this helps in any way, in an old air cooled lump like these motors, we need to be richer than 14.7:1 anyway and I’d guess that you’re actually not far away from OK in your upper Rev range. I’m guessing ambient temperatures in your neck of the woods are quite high too? Which is another argument for being slightly on the rich side of ideal.

    As to the FCRs being ‘over the top’ well, that was my initial gut feel, and I wish I’d had a £ for every time someone has said it looks ‘over carbed’. But, if you look at the flow tests Comnoz did, they came out very good, and all I can say having used them is that they are fabulous, with easy starting and great acceleration being helped by the ‘pumper’ and very clean and precise metering all they way through the range. Not synchronisation issues either!

    It’s just that I cannot answer you MPG queries unfortunately !
     
  4. Fullauto

    Fullauto VIP MEMBER

    Joined:
    Apr 13, 2009
    I hear you Nigel. I suppose it started because of a certain ex-member on this forum giving me a hard time over a lack of any hard data about performance advantages of my heads. I just didn't have the resources to do anything about it. I'm now down to one meal a day to finance these experiments. The problem I found is that there is a major shortage of information out there on Norton dyno runs. Trying to sort the wheat from the chaff is difficult, and without people like Jim Comstock, there would be almost nothing out there. As always, there is a lot of "well, I haven't done it, but I think that this is how it would go". So, I've decided to try and learn, ask direction, and generally try stuff so that I know if it works or not. Remember when we all thought that our Nortons made 60 BHP? Hohohohoho! Some still do!

    Anyway, I'll report back when I do some stuff to my "Nortan" 850.
     
    Brendan S likes this.
  5. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Norman White told me once that getting power from these motors is ‘all in the head’. And that has stuck with me whilst I’ve been playing around with mine.

    My main regret is not putting mine, a mk11a, on the dyno before I started out modifying it.

    As purchased, it ran well, I’d say better than most (as attested to by a member on the forum, it was ‘ a good un’).

    It had a single 36mm Mikuni. I checked the CR and was surprised to see it was actually only 7.6:1. But I would estimate it had somewhere between 35-38 rwhp.

    As you say Ken, all those owners who think their stock Commandos are putting out over 50rwhp and their Combats 65rwhp are sadly deluded !

    Hence my regret, I’d have liked to have known the starting point for certain. But never will.

    My ‘mk1’ build was with JS1 cam, 10.5:1 JS pistons and long rods, 35mm FCRs, Tri-Spark and box stock RH10 head. It clearly had more torque everywhere compared to prior, and its power above 4K was light years ahead, previously it just ran out of breath at 5k, afterwards it stomped right past that with ease. On the dyno it peaked at 56 point-something rwhp, so probably a 20hp increase.

    My ‘mk11’ build was as above, with Comnoz top end treatment. This included bigger inlet valves, careful porting job, and a slightly tighter radius on the tappets aimed at sacrificing a little peak rwhp for more torque lower down.

    Nevertheless, it still blew me away when it showed 64 rwhp. That much improvement from only the head really, really surprised me.

    So it currently has probably 28hp more than when I started, which is a 77-78% increase!

    It’s a shame I didn’t have a FA head to do this with, I just used my existing RH10, which is not as good a basis as one of your heads. But it still goes to show how much potential there is in these motors just ‘in the head’.
     
  6. gortnipper

    gortnipper VIP MEMBER

    Joined:
    Nov 11, 2013
    Remind us what exhaust you used on that 64 hp run, it was a Maney, correct?
     
  7. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Perhaps if you change the fiddle-factor in the software, you can make the dyno tell you what you want to hear. As I understand it, many inertia dynos have been set up to make a particular Yamaha V-max super bike read 150 BHP. If that is the method of calibration, what does 65 BHP at the rear wheel of a Commando mean ? (Is the system linear ?) If you are doing comparisons while making changes to the bikes set-up, the dyno is probably a very good tool. But I think an absolute reading of torque or horsepower might be very suspect.
     
  8. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    I'd be very interested to know the Dyno reading with the TM flatslide, I have had 32mm CV a 34 mm VM and a 36mm single mikuni on my 750,but I wasn't prepared for the difference a tm 40 would make ,I'd dearly love to run my bike on a Dyno back to back with the TM 40 and a pair of 32mm amals
     
  9. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013

    Stock 1 3/8 unbalanced pipes and peashooters actually !

    I tried the Maney type system before having the top end work done and it made a circa 5bhp difference, even more in the mid range.

    After the top end work, there wasn’t so much between them at all. The stock set up gave a smoother curve though.

    This surprised me. My assumption is that the reduced duration, due to re radiused followers, didn’t allow the Maney type system to work properly.

    I shall be experimenting with it again though on the ‘mk111’ build, which will be a 920 and have a different cam set up.
     
  10. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Al, as has been repeatedly stated, my posts refer to same dyno, same operator, and are offered to show the difference that the various approaches I have taken have made, via objective comparison, for the perusal and discussion and benefit of others.

    I make no claims of absolute power, nor of the righteousness of the approaches I have tried.

    It’s not rocket science mate.

    We’re not all as lucky as you, in having a standard engine that’s faster than anything else out there. Some of us seem to have to work a little harder at making some small gains.

    We look forward to some objective input from you. One day.
     
  11. Brooking 850

    Brooking 850 VIP MEMBER

    Joined:
    Oct 3, 2011
    Nigel, yes all the power and torque is in the head as my race motor can atest to.
    Yes displacement helps but is useless if the head doesnt work well.
    I am surprised Kens motor doesnt produce more than high forties though.
    The RH10 I have has standard Vv.s and the head job makes it work well with the 2 EX 1 system.
    I am building an 880 with a Full Auto head so will be putting that on the dyno early next year.
    Regards Mike
     
  12. Fullauto

    Fullauto VIP MEMBER

    Joined:
    Apr 13, 2009
    Single carb, Mike. But what it loses in the top end is more than made up for at the low end and in the mid range. A delightful motor.
     
  13. pommie john

    pommie john

    Joined:
    Nov 18, 2005

    If that's full throttle all the way I'd suggest the air corrector jet is too small.
     
  14. pommie john

    pommie john

    Joined:
    Nov 18, 2005
    It says on the sheet it's a Dyno Dynamics machine not a Dynojet. These ones have a brake and are not a simple inertial dyno. They also tend to read a bit lower than a Dynojet.
     
  15. pommie john

    pommie john

    Joined:
    Nov 18, 2005

    I just re read this. I'm not sure that 12.8 is rich for full throttle on an air cooled engine.
     
  16. Dances with Shrapnel

    Dances with Shrapnel VIP MEMBER

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    Jul 8, 2011
    I agree with you.
     
  17. acotrel

    acotrel

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    Jun 30, 2012
    My comment about absolute readings on dynos was in reference to the comment 'it blew me away when it showed 64 BHP on the dyno'. What was the primary standard and method of calibration ?
     
  18. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Wow. Do you really not read before posting?

    The reason it ‘blew me away’ was because the 64rwhp was achieved with the same bike, same dyno, same dyno operator. The only difference being the Comnoz head work.

    So, I was blow away by the fact the Comnoz head work made approx 9bhp difference.
     
  19. Kvinnhering

    Kvinnhering VIP MEMBER

    Joined:
    Feb 16, 2011
    I aim at 12.5
     
  20. Fullauto

    Fullauto VIP MEMBER

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    Apr 13, 2009
    Great feedback! Onward and upward!
     
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