Commando HP and Torque

I was reading-up on dynos a while back. One of the most common ones was calibrated by putting a Yamaha V-max on it and making the dyno read its specifed horsepower - 150 BHP. That is OK for tuning purpoases, but it is PRECISE - not ACCURATE. PRECISE is when all the arrows land near the same place on the target - ACCURATE is when the arrows all land with their location near the centre of the target.
Horsepower is only about bragging rights, its actual value is not so important. 'Torque wins races' and most modern dynos are based upon torque - they measure the load when spinning up a weighted drum.
A test brake measures the load from a lever arm when the brake is applied. The load measuring device is calibrated with a dead-weight tester, and the horsepower calibration is traceable back to international standards.
The strength of a Commando engine lies in its torque and the gearbox is a torque converter. As you raise the overall gearing, you end up in the same place as a motor with a light crank and lower gearing, but your throttle response is worse. Close ratio gears and lean jetting, fixes the throttle response problem With close ratio gears, on each up-change you lose fewer revs. You don't wait for the crank to catch up. The revs are always where they need to be, to give you another surge forward. The heavy crank stores a lot of energy.
When I built my Seeley 850, I never believed it would be quick enough. But on a race circuit, it is at least as good as anything else. It is very deceptive. You can believe it is going as fast as it can, then you find more speed.
 
Last edited:
acotrel said:
.......Horsepower is only about bragging rights, its actual value is not so important. 'Torque wins races'......
Click to expand...
Power is a measure of the rate at which torque can be delivered, so it's all-important. A broad spread of torque can make up for less than ideal gearing but, taken to the extreme in, for instance, a machine with an efficient and infinitely variable transmission, a higher power, if peaky, engine will always beat a less powerful engine, regardless of how much torque it makes.
 
ggryder said:
Power is a measure of the rate at which torque can be delivered, so it's all-important. A broad spread of torque can make up for less than ideal gearing but, taken to the extreme in, for instance, a machine with an efficient and infinitely variable transmission, a higher power, if peaky, engine will always beat a less powerful engine, regardless of how much torque it makes.
Click to expand...
That might like be saying 'wars will always be won by the side which can produce the most'. A few years ago, that was the truth.
If you have peaky power output, you asre often at a disadvantage on tight circuits. Many people who rode two-strokes in the early 70s were forced to go slower in corners and get the bike upright before giving it the berries. Later inprovementis to two-strokes were usually about getting more torque. Whih a Commando engine, some people try to produce more top end when they cannot use the midrange effectively due to their bike's handling deficiencies.
'If you have a victim's mindset, you will be a victim' ? When you change anything, there is usually a downside. If you increase the trail on a two stroke, so the bike oversteers, you would probably crash halfway down a straight. Most of them are neutral-steering. With a Seeley Commando with a lot of trail, you can flick the bike into a corner and accelerate hard all the way around it. Try that with a two-stroke.
The issue with the standard gearbox, is loss of revs on every up-change. With a close box, you have a shorter distance to come up, to get back to maximum power
There is a lot of bullshit talked by some guys. One told me 'if you have a torquey motor, you don't need a close ratio gear box'. Another told me 'steering dampers only compensate for bad handling'. Both of those statements are wrong. Bikes always accelerate faster if they have close ratio gears. And an hydraulic steering damper tends to straighten a bike out if you get into a big tank slapper, by riding too fast. THe quicker the steering moves the quicker the rate at which the hydraulic pressure rises in the damper. All the rider has to do in a tank slapper, is wait until the bars stop crashing around, then very carefully regain control

I suggest you should go there and find out for yourself.
 
Last edited:
acotrel said:
That might like be saying 'wars will always be won by the side which can produce the most'. A few years ago, that was the truth.
If you have peaky power output, you asre often at a disadvantage on tight circuits. Many people who rode two-strokes in the early 70s were forced to go slower in corners and get the bike upright before giving it the berries. Later inprovementis to two-strokes were usually about getting more torque. Whih a Commando engine, some people try to produce more top end when they cannot use the midrange effectively due to their bike's handling deficiencies.
'If you have a victim's mindset, you will be a victim' ? When you change anything, there is usually a downside. If you increase the trail on a two stroke, so the bike oversteers, you would probably crash halfway down a straight. Most of them are neutral-steering. With a Seeley Commando with a lot of trail, you can flick the bike into a corner and accelerate hard all the way around it. Try that with a two-stroke.
The issue with the standard gearbox, is loss of revs on every up-change. With a close box, you have a shorter distance to come up, to get back to maximum power
There is a lot of bullshit talked by some guys. One told me 'if you have a torquey motor, you don't need a close ratio gear box'. Another told me 'steering dampers only compensate for bad handling'. Both of those statements are wrong. Bikes always accelerate faster if they have close ratio gears. And an hydraulic steering damper tends to straighten a bike out if you get into a big tank slapper, by riding too fast. THe quicker the steering moves the quicker the rate at which the hydraulic pressure rises in the damper. All the rider has to do in a tank slapper, is wait until the bars stop crashing around, then very carefully regain control

I suggest you should go there and find out for yourself.
Click to expand...
What you keep ignoring is the ‘if all else is equal’ point of the argument.

Of course I agree that extra power will not compensate for poor handling, wrong gear choices, low rider skill, etc. In fact it may make the situation worse.

But… if ‘all else is equal’ in terms of power delivery, set up, handling, rider skill, etc, etc. Then, apart from on the tightest tracks, the one with a power advantage will win.

At the low amateur levels (like me when I was racing) power is not such a big factor. I remember riders like Doug Jones on his Molnar Manx, he was un catchable to me, despite my (small) power advantage. He had a much better set up machine and much greater skill than me. But at the top level, so much is equal that the slightest advantage can make the difference between a win or not.

So, in general, the argument that race bikes don’t need power is just plain daft.
 
Porting is where I found the biggest HP boost. I thought my 1st Norton was a dog so I ported it and was stunned to get wonderful 2nd gear wheelies (low gearing). It was so fast that I decided to take it to the track. A roadracing career followed along with a flood of improvements. What started out as a street racer as in the photo below morphed into an all out roadracer and took me to 2nd place at Laguna Seca AMA 750 BOTT in 1984.

Commando HP and Torque
 
Madnorton said:
I have recent dyno figures for standard 750 and that indicates 48 at the rear wheel, a standard 850 will be low 40's. There are also dyno traces from the 70s in existence, I've seen them but not sure where the files are now.
Not sure how much testing Norton did, but I do know they had an engine dyno at Thruxton race shop, I was stood in the room they operated it in only 3 weeks ago.
One thing that also seems to be overlooked is spring rate and cam lift as this can also sap power. Its an area where trade off can be made, approaching max lift with high spring rates could work against what is trying to be achieved.
One successful race team from the early '70s used skimmed heads, HC pistons and most surprising a standard cam.
Click to expand...
In the experimental shop at the Marston Road factory, there were at least three Heenan & Froude "water brake" dynos (something in my feeble old brain says four but I can only remember three with certainty). I believe that one was set up to accommodate Villiers two-stroke engines; I'm certain that it could have been re-configured to suit Commando engine work but in practice, I think that it was not. These dynos were used extensively to evaluate and develop Commando engines (there was an electric brake dyno used for the Cosworth engine development but I don't know if this one had been installed specifically or if it had previously been used for Commando development). In addition, there were a group of "rolling road" dynos, brought over about winter of 1974 from BSA Armoury Rd. after that facility closed, for testing motorcycles off the end of the production line prior to crating and dispatch but I don't think that these were ever used for development purposes.

I began working at Wolverhampton in June, 1972, just in time for the festivities involved in the processes for analyzing the "Combat" engine problems, developing fixes for the recognized problems, and implementing the remediation measures. I was also there for the initiation of the 829cc project and the development of the engine to be known as the 850. With the blessing of John Nelson, Norton's International Service Manager (my boss's boss) and Alan Sargent, Experimental Department supervisor, John Baker and I took some surplus 850 prototype parts and built in the experimental department what became John's first "performance" 850 engine and installed it into my Commando, producing what was the first 850 Production Racer built at the factory (and perhaps the only one). John B was able to fit in a couple of dyno runs to check the setup on this engine build, especially to check on the effectiveness of his porting mods.

My engine used a skimmed head (thank you, Fred Barlow), standard pistons (with mild valve reliefs cut in), and a standard cam. The standard cam came from a discussion with John Hudson as I had asked his advice (John was quite severe with his opinion of the "Combat" cam, which I'd used previously, as being rough on valve gear). John pointed out that the "standard" Commando cam profile was the cam grind used on the 650 SS Dominator cam (the "Sports Special" cam) and - in John's usual humble opinion - this cam was the best performing of any used in Dominator/Atlas builds and offered good top-end power, a very effective mid-range power curve, and strong torque characteristics for acceleration throughout its wide power band.
Especially, I was most impressed by the acceleration characteristics of this engine build. It also showed good top end performance -- I think its fastest was at Ontario Motor Speedway, California. That track was a banked "quad-oval" much like "Indy" with a long straightway, also used as a dragstrip, with a high-speed, opening radius entry turn off the infield section onto the straightaway (there the acceleration on the 850 was like a dragster). I was running a 24-tooth gearbox sprocket and pulling Rpms up near the redline giving a calculated top speed of about 137 Mph at the end of the straight. I'm sure that there's a speed-to-horsepower converter out there somewhere. Oh, and BTW, I didn't have much confidence in a plain Smith's production-type rev-counter but someone had set up a speed-radar gun near the end of the front straight and his reading was ... 137 Mph. I will admit that I never had the .. erm, let's say, enthusiasm ... to hold the throttle 100% open though the banked turn as the exit turn onto the infield came up quick afterwards. It was a gentle turn and the exit off the banking was smooth and direct but with KR73/76 tyres and a fairing, my Norton wouldn't turn through that section in any normal way; the only way to turn was to counter-steer left-for-right into the banked turn, then counter-steer left-for-right to tighten up the right turn to go off the banking, then a quick counter-steer right-for-left to set up for the entry to the infield and then another counter-steer left-for-right for the actual entry turn. All this happened quite rapidly and had gained my full attention in test and practice laps before the race, so I'll admit to never carrying all the twist grip all the way through that series of turns. Still, it's a pretty good indication to me that the 850 could be made to produce a considerable amount of power.
And I'm sure that most of you will be familiar with John Baker's later 850 engine builds with Dave Rawlins, including a timed speed of over 140 Mph with an unfaired, stock-appearing 850 at L'autodrome de Linas-Montlhéry. This engine featured John's later porting suiting a "hotter" cam and was built up with a 4-S cam.
There's no reason for an 850 to be a slug.
 
Last edited:
I am certain there is no reason for an 850 to be a slug, However I probably think differently to engineers because I am a scientist. Over the years, I have come to the conclusion that engineers do not handle uncertainty very well.
For many people cause and effect is a two dimensional graph with a time axis - you have three variables. When you road race a motorcycle you have a lot more variables to play with, including the type and shape of the race circuit. To handle that situation, you need to recognise the patterns. If you have three variables and a time axis, the pattern becomes a landscape with a time axis, and it changes as you watch it You can visualise it in your mind. The low energy path is down in the valleys - you manage the trends.
However in a road race situation, there are a lot more than 4 variables. Horsepower and torque are just two of them. I do not race at Phillip Island because I think the circuit is too big, but it is a lovely place in which to race. My bike has very high gearing and a close ratio gearbox. The faster you go, the tighter the corners become. I think I would have a real problem racing my Seeley 850 on a circuit as big as Phillip Island.
The fastest part of Phillip Island circuit is the front straight and before it there is a large sweeping bend which goes on forever. As you go around the top and down that straight, the suspension on your bike pumps down and the bike becomes more stable. All feels sweet and lovely as you turn towards Southern Loop. That is where many guys end up rolling down the road and doing all sorts of antics.
The machine set-up which suits Phillip Island is a lot different to the set-up which suits Winton, Broadford or Mount Gambier. In all those other places, the horsepower is not as relevant as the torque handling anf brakes. On any of those circuits, if you get into a corner too hot, you need a front brake which you can gently apply to wash-off speed. When you do that in a corner, the front of the bike usually goes down and you tend to run wide a bit faster, until there is a point at which you have to take your life in your hands and accelerate. On Phillip Island, the speeds at which that sort of thing happens can be very high. Any crash there is usually a very big one.When I was a kid I managed to crash there, four times in one day. The drum front brake kept dragging, then it would lock when it had heated-up. I could not understand why my bike kept running off the bitumen.
I have found my Seeley 850 to be fast enough to win races, The main things it has are steering geometry which makes it oversteer when you accelerate in the middle of corners, a very sensitive and reliable front brake which is one-finger operation, and a gearbox which can get the best out of the motor. I don't think it makes much horsepower, but a gearbox is a torque converter, If you are super-fast in corners, you do not need to be so fast down the straights. As soon as I enter a corner on a tight circuit, I accelerate full blast - no sense-no feeling. When the back goes down, the bike will alays steer in the direction of lean. So I go under, not over,
When I practice, in corners I progressively brake later and further, and get on the gas earlier. That way I know what my bike is doing. The rear suspension setting determines the rate at which the bike will turn.
 
Last edited:
Blewdy Yaink said:
In the experimental shop at the Marston Road factory, there were at least three Heenan & Froude "water brake" dynos (something in my feeble old brain says four but I can only remember three with certainty). I believe that one was set up to accommodate Villiers two-stroke engines; I'm certain that it could have been re-configured to suit Commando engine work but in practice, I think that it was not. These dynos were used extensively to evaluate and develop Commando engines (there was an electric brake dyno used for the Cosworth engine development but I don't know if this one had been installed specifically or if it had previously been used for Commando development). In addition, there were a group of "rolling road" dynos, brought over about winter of 1974 from BSA Armoury Rd. after that facility closed, for testing motorcycles off the end of the production line prior to crating and dispatch but I don't think that these were ever used for development purposes.

I began working at Wolverhampton in June, 1972, just in time for the festivities involved in the processes for analyzing the "Combat" engine problems, developing fixes for the recognized problems, and implementing the remediation measures. I was also there for the initiation of the 829cc project and the development of the engine to be known as the 850. With the blessing of John Nelson, Norton's International Service Manager (my boss's boss) and Alan Sargent, Experimental Department supervisor, John Baker and I took some surplus 850 prototype parts and built in the experimental department what became John's first "performance" 850 engine and installed it into my Commando, producing what was the first 850 Production Racer built at the factory (and perhaps the only one). John B was able to fit in a couple of dyno runs to check the setup on this engine build, especially to check on the effectiveness of his porting mods.

My engine used a skimmed head (thank you, Fred Barlow), standard pistons (with mild valve reliefs cut in), and a standard cam. The standard cam came from a discussion with John Hudson as I had asked his advice (John was quite severe with his opinion of the "Combat" cam, which I'd used previously, as being rough on valve gear). John pointed out that the "standard" Commando cam profile was the cam grind used on the 650 SS Dominator cam (the "Sports Special" cam) and - in John's usual humble opinion - this cam was the best performing of any used in Dominator/Atlas builds and offered good top-end power, a very effective mid-range power curve, and strong torque characteristics for acceleration throughout its wide power band.
Especially, I was most impressed by the acceleration characteristics of this engine build. It also showed good top end performance -- I think its fastest was at Ontario Motor Speedway, California. That track was a banked "quad-oval" much like "Indy" with a long straightway, also used as a dragstrip, with a high-speed, opening radius entry turn off the infield section onto the straightaway (there the acceleration on the 850 was like a dragster). I was running a 24-tooth gearbox sprocket and pulling Rpms up near the redline giving a calculated top speed of about 137 Mph at the end of the straight. I'm sure that there's a speed-to-horsepower converter out there somewhere. Oh, and BTW, I didn't have much confidence in a plain Smith's production-type rev-counter but someone had set up a speed-radar gun near the end of the front straight and his reading was ... 137 Mph. I will admit that I never had the .. erm, let's say, enthusiasm ... to hold the throttle 100% open though the banked turn as the exit turn onto the infield came up quick afterwards. It was a gentle turn and the exit off the banking was smooth and direct but with KR73/76 tyres and a fairing, my Norton wouldn't turn through that section in any normal way; the only way to turn was to counter-steer left-for-right into the banked turn, then counter-steer left-for-right to tighten up the right turn to go off the banking, then a quick counter-steer right-for-left to set up for the entry to the infield and then another counter-steer left-for-right for the actual entry turn. All this happened quite rapidly and had gained my full attention in test and practice laps before the race, so I'll admit to never carrying all the twist grip all the way through that series of turns. Still, it's a pretty good indication to me that the 850 could be made to produce a considerable amount of power.
And I'm sure that most of you will be familiar with John Baker's later 850 engine builds with Dave Rawlins, including a timed speed of over 140 Mph with an unfaired, stock-appearing 850 at L'autodrome de Linas-Montlhéry. This engine featured John's later porting suiting a "hotter" cam and was built up with a 4-S cam.
There's no reason for an 850 to be a slug.
Click to expand...

Wow. That brings back some pretty cool Ontario memories. I managed quite a few AFM races at Ontario on my Production Racer in the '70s. I did a 150 mile Easter (1975, maybe) race there on the PR. It was two 75 mile sprints with a short break in between to change riders. I didn't have another rider, so did both legs myself. I could barely walk when I got off the bike at the end. Wish I had some pictures, but all I have from those days is a really grainy video converted from a Super-8 film taken by my wife. I really enjoyed that track.
 
Nigel, what you are saying about horsepower and all things being equal, is correct when it applies to MotoGP bikes. Most of their races become a power procession. With old bikes that does not usually happen. It is a mistake to look at modern bikes and work backwards. You need to look at a Manx Norton and work forward. I never play that power game because it is too expensive. All I need is enough power to stay somewhere near the lead bunch in races. My main problem has been to 4 speed close ratio box. It was perfect everywhere except coming off the start line. That is the reason I bought the 6 speed TTI box. What you lose before turn two in a race, is very difficult to recapture
 
lcrken said:
Wow. That brings back some pretty cool Ontario memories. I managed quite a few AFM races at Ontario on my Production Racer in the '70s. I did a 150 mile Easter (1975, maybe) race there on the PR. It was two 75 mile sprints with a short break in between to change riders. I didn't have another rider, so did both legs myself. I could barely walk when I got off the bike at the end. Wish I had some pictures, but all I have from those days is a really grainy video converted from a Super-8 film taken by my wife. I really enjoyed that track.
Click to expand...
When I first started road racing, I read a lot about racing on British circuits. I came to the conclusion that many of their circuits must have been more open and flowing than those in Australia. And American race circuits might be even more so. I was used to riding on public roads, but when I started racing, I found I could not use as much throttle without crashing. But I never had a Manx Norton. I never really knew what they were about, until I rode one. Japanese two-strokes were much easier, but never as enjoyable. I like to feel the hairs growing on my chest, but not so much my ring tightening with fear.
 
Last edited:
lcrken said:
Advertising copy quotes horsepower as 60 hp at 5,900 rpm, at the crankshaft, but no torque given.

Service manual quotes torque as 56 lb./ft. at 5,000 rpm.

Ken
Click to expand...
Torque ALWAYS = HP at 5250 RPM
 
As the revs rise in most motorcycle motors, there is a high point in the torque curve. If you use a close ratio gear box, you can stay near that point to climb in speed. Most of the advances in two stroke rasce motors were about improving torque. A peaky motor is usually less user friendly. A toquey motor in a lighter bike can get you around corners at a much higher speed then a peaky motor in any bike. With race bikes, we need to recognise patterns. What suits a power circuit such as Phillip Island does not suit a short tight circuit suckh as Winton motor raceway or Mount Gambier circuit. It is 'hirses for courses'. You might think that raising or lowringthe overall gearing can accout for any change in circuit size. But it is also the proportion of large sweeping bends and long strasights, compared with the number of tight bends and short straights. If you come omto the longest straight a Winton going 10 MPH fasterr than the others, the others need immense horsepower to pass you before the end of the straight. THe same does not apply at Phillip Island. Before you come onto the longest straight, there is an extremely long sweeping bend, which you can get around at full thottle on any bike. A top end motor really gets goimg on that. At a pinche ther are other places on the circuit where you can make up time. But for a Commando, it is probably pretty hopeless. I have not ridden there for years, back in about 1969, I crashed all over the landscape on that circuit. It is deceptively fast and definitely not the place to use drum brakes. I don't usually have a problem braking for corners, but Phillip Island catches-out a lot of young guys. When you sre on the circuit it feels lovely/
 
ashman said:
I built my 850 to Combat spec into the Featherbed frame its a lot lighter than the old Commando, revs a lot harder and does well over the ton and was built in my younger days when I was a light weight, now I am old and more wiser high speeds runs are not on top of my things to do so am happy to only go to the ton and not much more, our speeding fines are pretty high in my state so 50hp and up to 65hp for a non stock Commando is about right, but back in the 70s that wasn't too bad for any bikes of the times.
As for Hondas I have always owned Honda dirt bike even to this day, never owned a Honda road bike, I got into Norton's my mates got into Honda 4s back in the days, the Commando was a lot lighter around the same price new and sounded so much better than a 4 potter, handled so much better, but they always told me the Honda 4s were a lot more reliable, I still rub that in their faces as my Norton has always been reliable.
But really don't need to do much to make a Commando motor breathe fire all I did was a 2S cam grind, crank balance, port work and shaved head, carbs jetted and set right, open up exhaust system and a bigger spark and of course a lighter bike.
I wouldn't have a clue in the HP it has but it's so much better than a stock 850 at stock my 850 would valve bounce at 6500 rpm, now it revs freely so got to watch it if you let it loose, but its all about tuning for max HP, so 65hp be pretty close for a hot motor.

Ashley
Click to expand...
Yep….the older I get the faster I was ;)
 
Last edited:
The GPS dyno apps for your phone can be surprisingly accurate for cars. The biggest issue with the on a motorcycle is getting a good enough coefficient of drag. I am using PerfExpert at the moment as friends have had results within 1 to 4 hp of their dyno sheets. I am testing with a 0.5 and a 0.7 coefficient of drag, but I have no idea what a ball park figure should be.
 

Similar threads

E
QD rear wheel torque
Replies
6
Views
341
ewgoforth
E
johnm
Commando 850 petrol tank capacity and mileage
2
Replies
35
Views
1,264
850commando
850commando
ashman
Have someone asking advice in what to pay for a Commando
Replies
13
Views
388
Schwany
Schwany
F
Torque Settings
Replies
5
Views
387
Wardude
W
marshg246
Torque
Replies
5
Views
1,018
marshg246
marshg246
Back
Top