H.P mods ?

FWIW, Keep in mind that weight has a major effect on acceleration but very little affect on top speed.

acotrel said:

So an 850 Commando has as much power as a very good 350cc BSA Gold Star DBD32 or a 7R AJS ? ?
I often wondered why 500 cc Manx Nortons were so quick with only 50 BHP.. In Australia in the 1950s, the only bike which could beat them was a 100 BHP Norvin on a big circuit.

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That’s a fair point that puts a modern Manx replica into perspective, with 60rwhp and a dry weight of 260lbs it’s gonna feel like a bloody rocket ship next to a stock 850 Commando.

But at a price!

Fast Eddie said:

That’s a fair point that puts a modern Manx replica into perspective, with 60rwhp and a dry weight of 260lbs it’s gonna feel like a bloody rocket ship next to a stock 850 Commando.

But at a price!

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That's what you get for 40k and 70 years og development.

A fair point, well put !

Numbers aside, a good 500 Goldstar feels pretty gutless after riding a standard 850 Commando.
As a friend who owned one and toured extensively on it for thirty years said " When loaded with luggage, passing requires quite a bit of planning"
A 350 would be ....less.

Glen

Horses for courses again innit.

In the canyons or on a track day, a stock 850 Commando rider would have to dig deep to keep with a well prepared and well ridden Goldie. And well ridden on a Goldie means keeping it in the high rpm power band.

Your mate is a strange one I’d say Glen. Goldie‘s were production racers, highly tuned for peak power. A strange touring choice.

Over here the trend is to take a Goldie and fit low a CR piston, B33 cams, touring bars and touring footrests.

I just don’t understand why these guys don’t just buy a B33? Or judging by the way many ride, a B31 ??

Fast Eddie said:

Horses for courses again innit.

In the canyons or on a track day, a stock 850 Commando rider would have to dig deep to keep with a well prepared and well ridden Goldie. And well ridden on a Goldie means keeping it in the high rpm power band.

Your mate is a strange one I’d say Glen. Goldie‘s were production racers, highly tuned for peak power. A strange touring choice.

Over here the trend is to take a Goldie and fit low a CR piston, B33 cams, touring bars and touring footrests.

I just don’t understand why these guys don’t just buy a B33? Or judging by the way many ride, a B31 ??

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And then there are guys like us...

acotrel said:

old days

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worntorn said:

Numbers aside, a good 500 Goldstar feels pretty gutless after riding a standard 850 Commando.
As a friend who owned one and toured extensively on it for thirty years said " When loaded with luggage, passing requires quite a bit of planning"
A 350 would be ....less.

Glen

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The difference between horsepower and torque ? An 850 Commando has got more guts. Two-strokes are faster than four-strokes until they encounter a head wind. Then they can feel as though they have stopped. With some bikes, they are only powerful when they a revving high. If you slow a Commando down with a breeze, a hill or a load, it will still pull. When you raise the overall gearing with a close ratio box you exploit the Commandos' torque characteristic. It is the torque which gives the acceleration. Nothing stops a commando once the crank is spinning high.
I never believed in my Seeley 850 until I actually raced it. It is much better than I ever expected.

That post about using a hill as a dyno was interesting. I think you would get up a hill faster if you used a close ratio gear box to keep the revs up.

Fast Eddie said:

Horses for courses again innit.

In the canyons or on a track day, a stock 850 Commando rider would have to dig deep to keep with a well prepared and well ridden Goldie. And well ridden on a Goldie means keeping it in the high rpm power band.

Your mate is a strange one I’d say Glen. Goldie‘s were production racers, highly tuned for peak power. A strange touring choice.

Over here the trend is to take a Goldie and fit low a CR piston, B33 cams, touring bars and touring footrests.

I just don’t understand why these guys don’t just buy a B33? Or judging by the way many ride, a B31 ??

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For the years he ran the Goldie, that was his only motorcycle. His motorcycle budget was limited as he was building up his Machine Shop business, so he didn't have endless choice of models.
He bought the Goldstar for racing at Westwood, which he did. In the summertime, he put his wife on the back, loaded camping gear on and off they went, touring the mountains of BC. It worked, but one couldn't be in a hurry!
An 850 Commando is infinitely more powerful for this or even for solo unloaded road riding, again theoretical hp numbers aside.
I talked about this with our other Nigel (Tricatent)
He has a 500 Goldstar and an 850 Commando. Nigel likes to use the gearbox and lots of revs, so I'm sure the Goldie was giving all it had.
He will correct me if I'm wrong, but on that big climb out of North Van, his dyno hill, the 500 Goldstar managed about 75 mph ( not bad for a 500 single was his comment) while the Commando went up there at just under the ton.
Day and night!
I guess a 350 Goldstar would probably manage 65 -70 mph.
So the idea as suggested that a 350 Goldstar is as powerful as an 850 Commando is a bit off.
Picture a 350 Goldie screaming away at 65 mph in second gear when something goes by at 100 mph in top gear

I'm referring to simple power output on the road, not handling etc. On really twisty road, a good rider on a 25 HP Royal Enfield can outrun Ricky racers on litre Sportbikes, but it isn't a measure of relative power output.

Glen

For clarities sake, I was referring to a 500 Goldie.

I‘ve never dyno’d one or weighed one. But they’re claimed to be around 42bhp and 384lbs. So when all said and done, a Goldie produces similar power to an 850 Commando (in answer to your last paragraph).

Regarding your test, if it involved a high gear roll on type run then I see the Commando winning. Easily!

But with similar HP and less weight, I don’t see why the Commando should be doing 25mph more PROVIDED the Goldie was ridden at the required rpm in the correct gears.

Unless it’s from a standing start? In that case, with an RRT2 gearbox, the Commando wins again. Easily!

Of course I agree the Commando makes for a much better road bike for most people most of the time, and certainly a much better tourer, all that torque makes it easy and relaxing to ride fast.

I don’t think many folk will ever see a Goldie ridden properly on the road these days, peak power is at 7,000rpm IIRC. The Goldies I see on the road are pampered (understandably to be fair) and the owners wouldn‘t dream of seeing those revs on the tacho! But the few I have seen ridden properly are impressive.

I was referring to Acotrels comment or question.

"So an 850 Commando has as much power as a very good 350cc BSA Gold Star DBD32 or a 7R AJS ? ?"

As you mention, the DBD34 Goldie is rated at 42 bhp at crank, whereas a Commando 850 is rated 58-60 at crank. Also, the 500 Goldie produces a maximum torque of 31 ft lbs at 4700, crankshaft
The 850 Commando produces a maximum of 56 ft lbs at 5000 rpm.
T hat seems about right for 75mph vs 100.
A 350 Goldie is rated at about 32 bhp at crank, if memory serves.
These are all peak figures. If you look at mid range outputs, the difference is much greater.

I have this 63 650 BSA Super Rocket here, which has the same engine and same performance as a Rocket Goldstar, 46 bhp rated by BSA. Everything you read about the Rocket Goldstar indicates that it was slightly quicker than the DBD34 overall (46 vs 42)
So the Super Rocket is supposed to be really fast and the 850 Commando a slug.
I think there is something wrong with both of my bikes as the Commando is quite quick and the Super Rocket is a bit of a slug!

Glen

I was at a sprint meeting in about 1962. A Super Rocket BSA ran the fastest time of the day with just under 13 seconds for the quarter mile. I think a DBD34 BSA might be blown backwards by a head wind, more easily than a Commando.

Well that must have been a highly modified SR, or perhaps running on methanol.
One of the members of the A10 site restored 3 BSA A 10s.
After break in he dyno tuned all 3.
There was a plunger Goldflash, a Road Rocket and a late model high compression big valve Super Rocket like mine. The late model SR also has the hotter cam, the 357 Spitfire.
As I recall, the plunger Goldflash made 22 rwhp, the Road Rocket 26 and the Super Rocket was right around 30rwhp after tuning.
All made roughly the same amount of power up to 5000 rpm, although the Goldflash was the best up to 5000 by a couple of hp. The high comp hot cam SR had the least amount of power up to 5000 rpm but it did climb to 30 by 6500 whereas the others fell off.
This is interesting because above 5000 the bikes are quite annoying and buzzy to ride whereas below 5000 they are pleasant.
So the little power band from 5000 to 6500 with the big valve Super Rocket is nearly useless. The lowly 22 HP plunger Goldflash was his best performer for road use.

The 850 Commando feels like it has about double the output of the hotrod BSA. The BSA SR that I have is the highest performance iteration of the A10 engine, identical engine to the Rocket Goldstar.

Glen

Don't forget the 300mph headwinds down under, which blow every bike ever made backwards

worntorn said:

Well that must have been a highly modified SR, or perhaps running on methanol.
One of the members of the A10 site restored 3 BSA A 10s.
After break in he dyno tuned all 3.
There was a plunger Goldflash, a Road Rocket and a late model high compression big valve Super Rocket like mine. The late model SR also has the hotter cam, the 357 Spitfire.
As I recall, the plunger Goldflash made 22 rwhp, the Road Rocket 26 and the Super Rocket was right around 30rwhp after tuning.
All made roughly the same amount of power up to 5000 rpm, although the Goldflash was the best up to 5000 by a couple of hp. The high comp hot cam SR had the least amount of power up to 5000 rpm but it did climb to 30 by 6500 whereas the others fell off.
This is interesting because above 5000 the bikes are quite annoying and buzzy to ride whereas below 5000 they are pleasant.
So the little power band from 5000 to 6500 with the big valve Super Rocket is nearly useless. The lowly 22 HP plunger Goldflash was his best performer for road use.

The 850 Commando feels like it has about double the output of the hotrod BSA. The BSA SR that I have is the highest performance iteration of the A10 engine, identical engine to the Rocket Goldstar.

Glen

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I have a great running road rocket spec A10 I agree with all of the above

That sprint meeting at which the Super Rocket was the fastest - the other bikes were all road racers. To my memory, the Super Rocket was the only BSA twin which had dual carbs, back in those days. Also Nortons did not have dual carbs until the Manxman 650 came along in about 1963. The guy who rode the new Super Rocket was Eddie Poynter. He was the leader of a motorcycle gang. Everyone else who competed was a member of an MA affiliated club.
In those days, all road races were push-start, so first gear was usually quite high.

Acotrel said:

In those days, all road races were push-start, so first gear was usually quite high.

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First gear was high because they had a four speed close ratio gearbox.

When first gear is too low for a push start, we start in second gear!

The Super Rocket was built from 1958-63. It's a single carb bike from the factory.
At some point the factory offered a twin carb kit. Nowadays it's said to be more of a visual hop up than an actual performance item.
The twin carb Norton Manxman came out in 1961 for 1 year only. It morphed into the twin carb 650ss in 1962.
Norton started selling the twin carb 600 Nomad in 1957. They also offered twin carb kits for the 88 and 99 in 1958, 59 and 60. In 61 the 88ss and 99 ss were offered. These were twin carb bikes as delivered.
Glen

Wow! Has this thread gone into the weeds. That said, I'm really enjoying my education regarding the old BSAs. I would own a BSA for one reason, and only one reason.... that candy apple red and chrome gas tank!