Dyno run (2017)

splatt said:

So what horrendous anomalies have you observed so far ken

I find a std 850 34mm single carb comes on quite nicely at 3k starts to go flat about 5k and dead at 6k ,I don't want to go flat out in a straight line and putter down the highways about 65mph, but in the country on twisty road using the large selection of gears available to me 3 to 5 1/2 is plenty for me, still manage to scare the crap out of my self on enough occasions

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Well, it really is an eye opener. Things that you think are fact are not necessarily correct. I thought it was running pretty lean down low, but it's quite rich. I'm just ordering a few more jets of various types to see where that leads me. It leans out once you get out of the pilot circuit, but still not enough. I'm ordering a new #3 slide to see where that leads me. I currently have a #2.5. Uncharted territory for me. However, the bike is running and starting better than ever, so I'm sure I will be impressed even more when I get a bit closer. As I have said before, torque is this motor's strong point. With the standard motor, they do not indeed get serious until you get to 3000rpm. With the Fullauto Tech head it is noticeably stronger from idle on up. It provides a very useful bunch of low end power. What really surprised me was that the PW3 cam added AT LEAST as much again to the lower end and mid-range oomph. Maybe even more. By 3000 you are well under way! I have now had this combo for over 20,000 miles, so this is no ride around the block impression. I've had my Fullauto Tech head fitted for another 20,000 before that.

In the country on twisty roads, I don't bother with lower gears. If I have 40mph on the speedo, it's just a case of open the taps and you get a strong surge of power. I have a GoPro video with the camera mounted on the chin of my helmet, of a ride through the hills here, but I am anguished over putting it up here, as it shows me doing certain "things". It looks perfectly innocuous while looking at the tacho, but if you look closely at the speedo and equate it to the speed limits and advisory speed signs, you find yourself thinking that it's not too pedestrian after all. Not balls to the wall stuff, just good, sustainable, easy on an old body forward motion and fast enough to lose my bike for a month under current local legislation.

Changing the slide might make the transition from the pilot circuit to the needle jet better, but getting the needle taper and the needle jet internal diameter right, are much more critical. You will find that some Mikuni needles are the same diameter above the shoulder as Amal needles and the distance from the the clip grooves to the shoulder is the same. In Mikuni needles Ds are leaner than Fs when you open the throttle above one-third. Changing the slide will probably only affect the performance when you use less than on-third throttle. At that level the metering is mainly done by the parallel part of the needle.
If you are sensitive about the speeds you ride at on public roads, you have discovered the reason I only do road racing.

I've been running a #3 slide for a long time great highway economy, blues the pipes nicely, down to the second bend nearly, but I have wondered if it is what causes the mild knock when the tap was cracked open about 2k, it knocks once or twice and then its clear

The inlet port diameter affects the taper needle you need to use. As you open the throttle, you lose vacuum so need more fuel. With a bigger port, you lose vacuum quicker, so need a richer taper. If you've got small inlet ports, the needle taper should probably be leaner.

splatt said:

I've been running a #3 slide for a long time great highway economy, blues the pipes nicely, down to the second bend nearly, but I have wondered if it is what causes the mild knock when the tap was cracked open about 2k, it knocks once or twice and then its clear

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By a knock, do you mean detonation or a cough ? Both can be caused by mixture too lean. If it is a cough, it might be due to a cold motor, but detonation is serious, you cannot let that continue to happen. I only ever use #3 slides in any motor regardless of what carbs it has. There is usually enough adjustment elsewhere to cope if the slides are slightly loo lean. However I never ride my bike using less than about 4000 RPM.

[QUOTE="acotrel, . However I never ride my bike using less than about 4000 RPM.[/QUOTE]


Or on the road , or a long 2nd gear switch back incline ,or a nice fast sweeping country road, or through a nice forest past a nice lake to the top of a hill with a awesome view.................................................................................

Whenever I have done that, I've had the pleasant sensation of being surrounded by nature, but I have never enjoyed the view. That is why I like to sit in the passenger seat of my car, with my wife driving. All I see when I ride a motorcycle on public roads are things I might hit and places where the road surface might crash me. But I know what you are saying. There is a great sense of freedom, but it is an illusion. Continually watching my speed is not something that gives me pleasure. You should be able to ride as fast as conditions and hazards permit.- That is freedom.

Fullauto said:

Had the "Nortan 850" dyno'd last week with very interesting results.
View attachment 3110

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Fast Eddie said:

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!

View attachment 3114

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just for comparission, if anybody is interested:
this is my 750 with standard RH1 Head, two Wassel 9/30 evolution carbs, amal velocitiy stacks http://www.rgmnorton.co.uk/buy/mk1-conc ... s_1644.htm
CR 9,26 due to milled cylinder,
pazon sure fire,
rest should be standard.
this motor likes to be reved a little.

-sorry, we had problems to get a good ignition signal, so the graph is based on speed. we reved up to approximatly 6500 RPM. Torque graph is erratic, but max torque of approximatly 45,7ftlb (62Nm) seems reasonable. Upper PS Graph is at clutch, lower at rear wheel.

Most Commandos won't cop over 7000 RPM regularly without destroying themselves , so the torque factor is the most important. An improvement in torque allows higher gearing to be used. If the torque graph is erratic on the dyno, comparisons of torque before and after modifications, will be more difficult.

no750 said:

just for comparission, if anybody is interested:
this is my 750 with standard RH1 Head, two Wassel 9/30 evolution carbs, amal velocitiy stacks http://www.rgmnorton.co.uk/buy/mk1-conc ... s_1644.htm
CR 9,26 due to milled cylinder,
pazon sure fire,
rest should be standard.
this motor likes to be reved a little.

-sorry, we had problems to get a good ignition signal, so the graph is based on speed. we reved up to approximatly 6500 RPM. Torque graph is erratic, but max torque of approximatly 45,7ftlb (62Nm) seems reasonable. Upper PS Graph is at clutch, lower at rear wheel.

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Would be interested to hear how power at the clutch was determined, and what possible use it might be.

After the measurement on the rear wheel is done, the wheel is rolling out with engaged gear and pulled clutch , resistance is also measured . So losses in the drive train can be determined. The gap between both curves on the graph above is the loss of power in drive train.

Quick update. received a new slide and a few jets yesterday. The 2.5 cutaway slide was replaced with a 3 yesterday and a ride taken over varying conditions. Appeared to run even better with smoother, stronger response, especially off the bottom of the rev range. This morning, I replaced the #40 pilot jet with the #37.5 because the fuel/air ratio gauge showed a richness up to 1/4 throttle. Better again with the gauge showing more in the 13 range than before. Some richness still. I will try the #35 pilot jet and see where that takes me.

It has been an excellent learning exercise, where you think your bike is running really well and it improves with a few changes. It is now an extremely tractable, smooth, responsive motor that is an absolute delight on the road. As I lean out the bottom end, fuel consumption is improving and I think I will be back to the 65mpg range again. Once I get the low throttle opening settings pretty good, I'll move up and set the needle for best fuel consumption as the response is more than adequate at this level.

I've only got two weeks before the bike is picked up and taken to Melbourne so, of course, I want it to be as good as I can get it in the time available. I'm more than happy with how it's progressing and 160 miles from my Roadster tank will be most useful once I get into the highlands of Victoria and southern NSW.

On the whole, a very worthwhile exercise and I recommend it for fine tuning your Commando. Overall, I have absolutely confirmed that I know nothing, and that I had a complete collection of wrong assumptions.

What did you do for a reference point on the throttle, tape and break down into 1/4ers ?
Its an interesting exercise isn't it and now you would probably never piss around without a gauge
Have you noticed a increase in temperature ? although your head probably doesn't leak oil and start to smell like mine used to
Interstate tank then you can start having real adventures no more looking for a servo every 160 km

splatt said:

What did you do for a reference point on the throttle, tape and break down into 1/4ers ?
Its an interesting exercise isn't it and now you would probably never piss around without a gauge
Have you noticed a increase in temperature ? although your head probably doesn't leak oil and start to smell like mine used to
Interstate tank then you can start having real adventures no more looking for a servo every 160 km

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Seat of the pants and approximation at this stage due to not having enough eyes to manage the inputs and stay on the road.
It is indeed interesting! Ah. The Interstate tank is being prepped at the moment. I just got my new Corbin from CNW and my old one will be modified to suit the Interstate tank. Another part of the project that will be done a little differently to the norm.

Fuel range is not a problem. That's 160 MILES, about 265km. That means over 500 km with the big tank.

Fullauto said:

The Interstate tank is being prepped at the moment. I just got my new Corbin from CNW and my old one will be modified to suit the Interstate tank. Another part of the project that will be done a little differently to the norm.

Fuel range is not a problem. That's 160 MILES, about 265km. That means over 500 km with the big tank.

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Ken you will really like the Interstate tank. Oodles of fuel on tap. I have never yet had to use my reserve tap on my Interstate but I have on my Roadster. You may wish to choose an Interstate handle bar 063170, as they are just a little wider and you are seated back further on the frame. I tried roadster bars but me being 5' 8" made my arms too straight for long distance riding. YMMV Merry Christmas and a Happy New Year.
Cheers,
Tom

CanukNortonNut said:

Ken you will really like the Interstate tank. Oodles of fuel on tap. I have never yet had to use my reserve tap on my Interstate but I have on my Roadster. You may wish to choose an Interstate handle bar 063170, as they are just a little wider and you are seated back further on the frame. I tried roadster bars but me being 5' 8" made my arms too straight for long distance riding. YMMV Merry Christmas and a Happy New Year.
Cheers,
Tom

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Hi Tom ! No, I'm doing things a little differently to most. As usual. My Corbin for the Interstate tank will have the front part, that you don't use anyway, cut back, so that the seats will be mounted in the same place. Hence, I will have the same riding position with either tank. The knees will be splayed, but, because of the riding position, they are splayed with the Roadster tank anyway, so I'm anticipating the same feel. This means that I can change from an around town bike to a long range express in about 15 minutes. I don't think anybody has done this before. The usual problem with the Interstate tank is that you usually need to have rearsets fitted, which I don't personally like for a couple of reasons. With standard foot pegs you are usually gripping the tank with your knees to stop you sliding back on the seat. This becomes extremely tiresome. More so with the Interstate tank.The Corbin works because your bum is perfectly positioned with a, well, bumstop, which relieves the pressure on your thighs. The Corbin actually makes total sense of the riding position, unlike the original.

That’s how Matt does it at cNw Ken. He did the same for me, I have the same plan as you, to be able to change over quickly twixt the two. Mines still at the painters though...

Fast Eddie said:

That’s how Matt does it at cNw Ken. He did the same for me, I have the same plan as you, to be able to change over quickly twixt the two. Mines still at the painters though...

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I think it's a good plan. Mine's not yet at the painters. It's being coated internally first. I was just going to use the Roadster side covers and paint the Interstate tank the same Tangerine. But a couple of Interstate sidecovers came up, so now it's going to be metalflake silver. It gives me fifteen minutes to get home and change the bodywork over before the cops arrive ! What orange Norton ? The biggest flakes I can get and inch thick clear. Traditional Norton. Have a great Christmas !

Ken, when you are changing the jetting in your carburettors do you always use the same bit of road for testing ? When I jet my Seeley 850 , I have a certain section of a race circuit which I know very well, so if I get an improvement - I am very aware of it. I think that doing this on a public road is very much more difficult. When I was a kid, I had hotted-up road bikes and I don't think I ever got them jetted right.

acotrel said:

Ken, when you are changing the jetting in your carburettors do you always use the same bit of road for testing ? When I jet my Seeley 850 , I have a certain section of a race circuit which I know very well, so if I get an improvement - I am very aware of it. I think that doing this on a public road is very much more difficult. When I was a kid, I had hotted-up road bikes and I don't think I ever got them jetted right.

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Why would he have to , the whole thing has been about fitting a O2 sensor and getting real time readings from real time riding