Commando HP and Torque
- Thread starter jsnorton
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I have often wondered if those figures are real or if they were fever dreams of the marketing department like the US auto industry of that time. In some cases GM for example rated engines far lower to appease corporate 10:1 power to weight edicts. In other cases they were far inflated.
One listing for my G80cs shows 39hp. which I seriously doubt. OHC Manxes of the day were around 50.
One listing for my G80cs shows 39hp. which I seriously doubt. OHC Manxes of the day were around 50.
Fast Eddie
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Mart UK
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I find my 850 pulls slightly quicker than a mate's modern RE Interceptor 650. That has a claimed output of 47hp and dyno results @c.40hp. Low 40s looks about right to me.
ashman
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Does it really matter I am happy to get over the ton and get there pretty quick, they have plenty of grunt when needed, well mine does with the works done to it and at the time they were pretty good, I could blow off my mates on their Honda 4s, but they still put crap on my choice of new bike, I still own its and they no longer have their Honda 4s 
and don't I still let them know.
and don't I still let them know.
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I have owned Hondas in the past, one that would blow through the ton and keep going till I chickened out. Yet I had a miserable time selling them. Seems I always waited till after the new model came out. They don't hold resale value well but they're reliable transportation. Now the British and German bikes? I've had no trouble selling and had offers on the ones I don't want to sell. Mostly they'll break the ton.Does it really matter I am happy to get over the ton and get there pretty quick, they have plenty of grunt when needed, well mine does with the works done to it and at the time they were pretty good, I could blow off my mates on their Honda 4s, but they still put crap on my choice of new bike, I still own its and they no longer have their Honda 4s
Richard Tool
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What about 750 Combat motor’s claimed 65 hp ? ( presumably @ crank ) Anyone know for sure ?
ashman
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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
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
Fast Eddie
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No, but my guess would be high 40’s. Maybe low 50s.
I believe a race shop prepared Combat would be 65 at the crank. But not a production line job.
Hemmings, White, et al all say that the power is in the head work. My own experience on my 850 was 55rwhp with work on cam, carbs, CR hike, etc and 64rwhp on same engine / same Dyno, after Comnoz head work.
So, irrespective of the value of the actual numbers per se, the relative increase with good head work is rather remarkable IMHO.
Therefore, I’d suggest that to get anywhere near the factory claims, they wudda been race shop blue printed… inc port work.
And what you got off the production line was a fairly random result, but was somewhere between a lot lower and a freakin’ lot lower than that !
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I had my bike on a Dyno at a Norton rally in New Hampshire ,1973 Norton 850 and it topped out at 43HP on the rear wheel. I cant figure out how attach a picture or I would post the results from the machine
Mart UK
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Is it completely stock?
Mine go
My 1973 850 put out 44.5 hp. The only modifications that might potentially improve performance are lightened/ polished rockers, motormite brake booster valve, boyer Mk III, and r/d valve springs with titanium keepers. I doubt any of that would be worth much in the way of power.
ashman
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To me it's just numbers, HP from the crank or rear wheel, myself go by the seat of my pants HP, stock motors are restricted in how much HP they produce do work on the motor and make things breath better and get that burned gasses out quick but still keep a bit of back pressure from the exhaust all plays a part on any motor, and every motor will be different whether stock or worked, then there is wear and tear, new motor/old motor and then finding that sweet spot where the motor preforms best.
I worked at a TEC College (TAFE) for 31 years and for 6 years in the auto/motorcycle workshops they had a car dyno as well a MC dyno the students have comps to compare HP outputs, also seen a lot also go bang trying to prove things and a few fires as well, the dyno rooms were well set up, sound proof, fire proof and crash proof but accidents still happened from not going by the safety rules but of course young ones knew better.
I worked at a TEC College (TAFE) for 31 years and for 6 years in the auto/motorcycle workshops they had a car dyno as well a MC dyno the students have comps to compare HP outputs, also seen a lot also go bang trying to prove things and a few fires as well, the dyno rooms were well set up, sound proof, fire proof and crash proof but accidents still happened from not going by the safety rules but of course young ones knew better.
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The only thing different back then would have been a Boyer. Everything else would have been stock
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In Australia, all calibrations are supposed to be traceable to the standards in the National Measurement Laboratories. The 50 BHP of the Manx was probably measured on a Heenan and Froudr test brake and is probably pretty genuine. In the early 1960s, I watched Jack Forrest trounce all the Manx Nortons in a race, with a 650ss, so a 650ss probably delivers much the same as a Manx. I think any Commando would be a bit slower. Theit bigger capacity would not mean much.
The dynos which are currently used measure torque and the calibration of some is adjusted so they read a certain value for a Yamaha Vmax. The calibration is not usually based upon the normal measurement standards.
If you ride a genuine petrol fuelled Manx, you can get a basis for comparison when you ride other bikes down straight roads. My mate's 650cc Triton delivers much more power than a Manx. It is faster in a straight line. But not around corners. My Seeley 850 might be slightly faster in a straight line, but only because it is faster as it enters the straights. I accelerate hard from much further back in corners.
The dynos which are currently used measure torque and the calibration of some is adjusted so they read a certain value for a Yamaha Vmax. The calibration is not usually based upon the normal measurement standards.
If you ride a genuine petrol fuelled Manx, you can get a basis for comparison when you ride other bikes down straight roads. My mate's 650cc Triton delivers much more power than a Manx. It is faster in a straight line. But not around corners. My Seeley 850 might be slightly faster in a straight line, but only because it is faster as it enters the straights. I accelerate hard from much further back in corners.
