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It's a long way to 920 type(rary)

Discussion in 'Norton Commando Motorcycles (Classic)' started by yves norton seeley, Jan 14, 2018.

  1. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Where does this argument go guys? We know how the war ended after all.

    Please let’s not de-rail Yves’ great thread.
     
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  2. Jagbruno

    Jagbruno

    Joined:
    Jan 6, 2014
    Agreed.

    It was just a comparison, not a political statement. I could have mentionned the P38 Lightning as well, but I kept it British, by Jove.
     
  3. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    The comparison about the lovely exhaust note was a good one.

    The debate about WW11 equipment casualties was also interesting, but surely shouldn’t continue further.
     
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  4. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Its all good, we found out how to get Ludwig out of his fox hole!:D
     
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  5. Jagbruno

    Jagbruno

    Joined:
    Jan 6, 2014
    Hi there, from Yves on another thread yesterday, this looks *much* better:

    Great day to day: I put the 920 big valves Seeley Codo on a dyno again, first time after the tuning from the inlets, you remember how disapointed I was after the first dyno run before the tuning of the head 62 HP and no torque...
    But to day: 69.17 HP on the back weel and a max torque 71.6
    The temperature was 30 degrees celsius and you can see on the curve from the analyzer that the mixture was way to rich.



    [​IMG]

    [​IMG]

    Yves
     
  6. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    Is this the same dyno as before?

    Either way, great result Yves.


    Glen
     
  7. Jagbruno

    Jagbruno

    Joined:
    Jan 6, 2014
    Not the same Dyno, but looking *very* good...
     
  8. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    As you can see on the A/F ratio the mixture is way to ritch, for sure around 4.500 RPM, so I will go down with the needle to have it leaner, as you can see on the graphs also the torque and HP go's down at 4.500 also, so let's try
    Yves
     
  9. WZ507

    WZ507 VIP MEMBER

    Joined:
    Dec 26, 2013
    Nice to see the great power numbers and I’m sure you’re breathing easier now. Perhaps a night out with your favorite girl, Stella Artois, to celebrate?

    Regarding the A/F ratio, assuming the dyno pass is conducted at full throttle, the needle should be fully withdrawn from the needle jet and should have no influence on the fuel mixture. Perhaps you meant "go down with the main jet to have it leaner"?

    At full throttle the fuel mixture should be solely controlled by the main jet and air correction jet. I could see that if a mismatch of needle and needle jet were employed, where a long, large dia needle was not fully withdrawn from the needle jet at WOT, the needle circuit could then control the fuel mixture, but with normal selection of needle components this should not be the case. If this were the case (needle and needle jet controlling fuel mixture at WOT), you should be able to remove the main jet from the carb and observe no effect on mixture strength, since it would then be solely metered by the needle circuit.

    The fuel curve looks like it might benefit from a larger air correction jet, to both delay recruitment of the main circuit and lean it slightly, and a smaller main jet to get up to the correct A/F ratio. Eager to hear how things work out as you keep dialing it in.
     
  10. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    Hi WZ 507,
    First of all, I never drink a drop of alcool
    The thing I try to do first is make it leaner at 4500 RPM, later I will work on the air jet and main jet, at the moment the main jet is 8 points larger as before the changes on the engine and I keep the air jet like it was before
    The other thing is that the FCR have a aceleration pump, so on the dyno you must keep the throttle open at low RPM to avoid a fals reading becouse of the injection of extra fuel.
     
  11. cjandme

    cjandme

    Joined:
    Feb 5, 2011
    Hello Yves, didn't you say earlier in the thread that the bike felt great when you were riding it. Much better than before etc... Well I was wondering if it being a little rich might not be such a bad thing out on the road. It is still a new motor and needs to be run a bunch to get everything seating and bedded in and so forth. I will add that I don't have anywhere near as much experience with engines as you or jagabruno or ludwig or nigel or most of the other guys here, but lean is bad right and too lean is dangerous. Just thinking outloud...Cj
     
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  12. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    I wouldn't be surprised if you find 70+ hp once the motor is fully loosened up.
     
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  13. Jagbruno

    Jagbruno

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    Jan 6, 2014
    In fact, I would be surprised if it didn't!!!
     
  14. o0norton0o

    o0norton0o

    Joined:
    Apr 27, 2015
    A 70 HP commando engine for the street is impressive Yves, once you get the fuel mixture adjusted, I bet you get a few more HP's from that adjustment too... How do you measure fuel/air mixture??? an O2 sensor in the exhaust pipe???
     
  15. Jagbruno

    Jagbruno

    Joined:
    Jan 6, 2014
    I just spoke with Yves...he has tweaked his FCR 35's a tad leaner and he reports Warp 8 -grade acceleration. Watch this space for his colourful comments.

    (He has very kindly offered me to try out his spaceship, which I'll do next week...hehehe).
     
  16. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Yves,
    Based on my own playing around on the dyno, that richness could easily be costing you 3-4 bhp I think...
     
  17. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    Hi There, The mixture is analized on the dyno with a Lambda sensor in the exhaust. To day I was working on the FCR: I lower the main jet with 8 points, put the needle clips one notch higher, and go down on the pilot jet with a few points, probably to match becouse after adjustement of the idle speed when you rev the bike in neutral and release the throttle the revs hang up a few hunderd RPM above idle speed, then drop to idle, this is a sign that the idle mixture is to lean with the smaller pilot jets, I try to compensate with turning out two turns on the fuel screw, it was better but not perfect, I have to order new pilots jets, a size between the old one and the new one.
    I did a road test ride with the Seeley and I gat the feeling that the torque was better from 3K on, difficult to say becouse we speak about 2 or 3HP, we will see on the dyno
    soon...
    Anyway, when you take a turn in thirt of even in fourth or fifth gear and you open to WOT, you feel the Seeley living, is like sitting on a wild horse, but so far I keep it under control.
    At the moment I have a question, some persons claim to find 100HP on a Codo engine without turbo or blower, if I see what you need to do to find 70HP, I am asking my self
    what to do to find the 30 Hp left ???
    Yves
     
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  18. 84ok

    84ok

    Joined:
    Aug 10, 2014
  19. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    See the 84ok links in the above post and note what's already been achieved by Herb Becker. Beyond that - To get another 30 HP you might have to copy the characteristics of the Harley XR 750 because that's the most powerful pushrod twin valve. They get 90 to 100 hp out of a 750cc. For starters you have to move the valves so they are further apart (not just re-angle). You need .250" between the valves when they are on their seats and that means welding up the port bowls and re-shaping everything. When you get .250" between the valves then you can use wild cams with 100 deg lobe centers (the only way to realize a Nortons full potential). Then you need longer rocker arms to fit the new valve locations and to give you more lift (increased rocker arm ratio) with the available Norton cams. The longer rocker arm is available but that's another story.

    You'll have to go to a JS3 or Sifton 480 cam and twin free breathing exhaust pipes. You'll need 10-1/2" length from the end of the velocity stack to the head.

    It won't be cheap and it will take lots of time and development - but the technology exists - it just needs to be applied. Most of it is already laid out with the "Narley ports". This would be breaking new ground as no one has taken a Norton this far. The head would be very expensive with many hours of "Cobrahead" port shaping and the installation of huge valves. There would be so much modification that you may as well start with a stock 750 head.
     
    Last edited: Apr 25, 2018
  20. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I think that achieving another 30bhp would require work that made the bike unsuitable, or at least unenjoyable, on the road.

    Huge cams, huge ports, even huger carbs, huge CR, and huge revs!
     
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