Dyno run (2017)

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Had the "Nortan 850" dyno'd last week with very interesting results.
Dyno run (2017)

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.
 
I reckon you’d have over 50 horses, with little or no detriment to torque, if you fitted twin carbs.
 
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.
 
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.
 
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!

Dyno run (2017)
 
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!
 
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.
 
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.
 
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.

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

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
 
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
 
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! ...

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....
 
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

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.
 
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
 
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