Commando Top Speed?

Classic Norton Commando Motorcycles.

Re: Commando Top Speed?

Postby Jeandr » Sat Jan 01, 2011 7:54 pm

Hobot, are you sure you didn't fit a speedo showing Kph rather than Mph :?:

It's not that I don't believe you, but I have stopped believing in Santa Claus a few years ago

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Re: Commando Top Speed?

Postby highdesert » Sat Jan 01, 2011 8:02 pm

Hobot, with all due respect, there is NO WAY a single 34mm Mikuni will flow enough to get anywhere close to the top speed you claim from your Combat.

You are underpowered with that single carb setup. Do your bike a favor if you want acceleration and top end over simplicity, two carbs flow better than one.

You are the only person I have ever met or read that believed otherwise. No offense, but you are wrong on this.

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Re: Commando Top Speed?

Postby Jeandr » Sat Jan 01, 2011 8:06 pm

Rohan wrote:
Jeandr wrote:I don't want to call anyone a liar, but 100Mph is really moving on public roads,

Jean


Have you been on an English Motorway ??

First time I was on one, I wondered if the speedo was showing 70 mph, the legal limit, or if the speedo was secretly in Km/hr by the speed things were overtaking me...


I watch Top Gear and I know in some countries people know how to drive fast or at least they know enough not to pull out for to pass and stay in the fast lane until they notice their nostrils are clean. In Canada (and in the US) people barely look forwards so expecting them to look what's coming up at twice or three times the legal limit is a fantasy.

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Re: Commando Top Speed?

Postby hobot » Sat Jan 01, 2011 10:36 pm

Hianddry, I could not believe it either when seller was telling me how fast he rode the locally famous Combat, 120+. His dad had small engine shop that was prior a motorcycle shop that sold it off showroom after being the test bike to sell the others. Its kinda scary to me to go the ton on my SV650 and factory Combat but not on Ms Peel as could get there so quick and was so smooth and stable. I spent a few years learning and exploring fast riding but had too many close calls in blinds, like running over crests @ 120 to almost run up a troopers squad car. SV650 performance figures are well established and it a mere girls beginner bike in power and to me handling too compared to a good Combat and not in same league as Peel. This is a top speed discussion not practical daily survival routine. I know a bunch of 600's that may take issue that mere 34 mm being up to the job of spanking them. Also had over a dozen Monster 900 riders hiding Ms Peel from sight with them all squatting down of packed in close arguing over where the turbo charger was hidden! - as I'd already installed the vac/boost gauge. Most of them almost fell over backward when told - not installed yet. This is a public forum my words are being recorded, I don't want to be embarrassed proving up objectively what my Commando is capable of, so wait and see if I'm misleading anyone.

I can configure factory Trixie to past Peel accidental set up, standard head, Miki 34 carb and the 2-1-mega exhaust and put 22 T on or 21T with belt drive.
One strange feature that may count, I was in rush to get rings broken in waiting on CHO head lost for a year+, so just crudely cut out a fiber composite gasket with rough over hang into air flow plus the lip of the 32 mm manifold to small head ports. Hey just for timid break in use, Boy Howdy it sure woke up once 1000 mile run in done and tried to break her to know if reliable or not.
When component by component Peel got re-configured to normal hot rod configuration, CHO head 6 mm valves and dual Amals 32's, matched air passages, she stage by stage dropped to the normal so so performance listed above by majority of owners, barely able to touch 120 and too long to get there to not be scary hanging on and on in sections that allowed it. I have timed my runs too, so Smiths clocks are close enough even if 3 mph off.

Personally I'd like a two barrel carb, one small barrel and one big one.
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Re: Commando Top Speed?

Postby hobot » Sat Jan 01, 2011 10:59 pm

This interesting read on the 'Yellow Submarine" I quote what most strikes me between the eyes as anyone can just buy more power but no capability.

A lot more + photo's in here
http://www.motorcyclespecs.co.za/model/ ... ro_rac.htm
The genesis of this reputation wasn't merely the lack of suitable competition. The traditional Commando qualities were elevated to their highest pitch in the Submarine, and it was really those qualities that set it on the trail to victory. Because of the engine's vast reservoir of torque, the Commando pilot could dial his speed as though his twistgrip were a rheostat. Further, the standard Commando's fundamental agility was sharpened by the chassis tweaks of the Submarine until the bike was so stable and responsive that it could be ridden anywhere on the track, whether on a long straight or off-camber decreasing-radius turn. The generous (for the time) suspension travel gave the Production Racer a soft ride almost unknown among racers of the day, allowing the rider to concentrate on racing rather than just staying aboard. At long tracks notably the Isle of Man—the fatigue-reducing aspects of the Commando played a decisive role, for coupled to the plush suspension and superbly comfortable riding position were the Isolastic engine mounts, which sopped up virtually all the bad vibes the bike's vintage engine offered up. As a result of this honing of the standard Commando's best characteristics, the word got to Europe's (and even, to some extent, America's) street riders that the Commando won its races not because it was hand-grenade quick or ridden by win-or-die kamikaze pilots, but because it was somehow fundamentally different from all the other Britbikes that had soldiered on with vertical twins in the past.


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Re: Commando Top Speed?

Postby Carbonfibre » Sun Jan 02, 2011 4:34 am

Its very very easy to post BS on chat forums, but very much harder to back this up with anything even vaguely resembling fact!
Trouble is with this sort of rubbish, is that those that dont know better tend to believe it, so in some cases yet another urban myth comes into being.

In threads concerning top speed, in general it seems that any requirement to have rear wheel BHP figures that are related to the speed claimed, is something that is entirely irrelevant! In the real world any reasonable 10 yr old Jap 600 four will eat something like a Commando alive, both in terms of performance and handling.

Something that seems to be entirely forgotten by some people posting in regard to older classic bikes such as the Commando, is that these are vintage machines, and as such its pretty silly carrying out extensive modifications, which in some cases seem to be designed to make them perform more like a modern machine.

In real terms its very very difficult to make an old classic bike perform anything like a modern bike, so why not just enjoy as is, and simply change very poor OE parts such as carbs and ignition, which makes the bikes nicer to ride and much more reliable?

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Re: Commando Top Speed?

Postby daveh » Sun Jan 02, 2011 5:38 am

One of the things that attracted me to the Commando is that it represents a challenge to get it to perform to its optimum. Commandos have bags of potential but any number of factors have meant that only a minority ride and perform as they should. People were modifying Commandos since the factory began making them and they haven't stopped. Why should they? If they could have fitted 4-valve heads and EFI back in the day, they would have. I've had a lot of fun over the years making or watching people I know make a variety of bikes go faster. In the mid-1980s, a friend of mine even tuned an AJS 'Lightweight' 350. I sprinted it (and got real times and speeds) and we got a lot of satisfaction and enjoyment out of it.

No-one here disputes that a street Commando can't live with modern bikes except under special conditions. That wouldn't stop me from squeezing another 10 hp out of my bike if I could justify the cost! I already have my shopping list...

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Re: Commando Top Speed?

Postby Reggie » Sun Jan 02, 2011 6:01 am

Carbonfibre wrote;
classic bikes such as the Commando, is that these are vintage machines, and as such its pretty silly carrying out extensive modifications


I'm therefore very, very, very silly! But I am very happy as well! :D :D
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Re: Commando Top Speed?

Postby Carbonfibre » Sun Jan 02, 2011 6:05 am

Certainly its a challenge to get an old Norton to perform at its best, and this can be enjoyable to do. In pursuit of this though, it seems some posters here simply discount the basics such as carb, ignition, exhaust, cam timing etc, go straight ahead with very costly and involved modifications, that may well not have the desired effect.

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Re: Commando Top Speed?

Postby Rohan » Sun Jan 02, 2011 6:57 am

daveh wrote: If they could have fitted 4-valve heads and EFI back in the day, they would have.


I suppose you have heard of the Piper 4 valve heads for the Commando ?

Don't know anything about them, but one of the books on Nortons has a pic of one of them, with the comment that when the factory tested it, they used valve springs that were too strong, and didn't get very good results .

Anyone know any more of them ?

When someone tried a 4 valve version of the head for a Manx, they supposedly got another 10 hp out of it, which is a lot when they only produced 50 bhp back then (Its a 500cc) . Civilisation will be dead before folks stop trying to get more hp of Manxes ?, whose only purpose in life was to race after all, and which class is still going strong...

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Re: Commando Top Speed?

Postby Jeandr » Sun Jan 02, 2011 7:44 am

Carbonfibre wrote:Its very very easy to post BS on chat forums, but very much harder to back this up with anything even vaguely resembling fact!
Trouble is with this sort of rubbish, is that those that dont know better tend to believe it, so in some cases yet another urban myth comes into being.

In threads concerning top speed, in general it seems that any requirement to have rear wheel BHP figures that are related to the speed claimed, is something that is entirely irrelevant! In the real world any reasonable 10 yr old Jap 600 four will eat something like a Commando alive, both in terms of performance and handling.

Something that seems to be entirely forgotten by some people posting in regard to older classic bikes such as the Commando, is that these are vintage machines, and as such its pretty silly carrying out extensive modifications, which in some cases seem to be designed to make them perform more like a modern machine.

In real terms its very very difficult to make an old classic bike perform anything like a modern bike, so why not just enjoy as is, and simply change very poor OE parts such as carbs and ignition, which makes the bikes nicer to ride and much more reliable?


A very hearty +1 Make them look good, sculpt them to your style or liking, but expect them to equal or better even a smaller displacement modern bike, no way.

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Re: Commando Top Speed?

Postby daveh » Sun Jan 02, 2011 8:00 am

Rohan wrote:I suppose you have heard of the Piper 4 valve heads for the Commando ?

When someone tried a 4-valve version of the head for a Manx, they supposedly got another 10 hp out of it, which is a lot when they only produced 50 bhp back then (Its a 500cc) . Civilisation will be dead before folks stop trying to get more hp of Manxes ?, whose only purpose in life was to race after all, and which class is still going strong...


Never heard of the Piper heads for Commandos. I would have thought that you would need to get the engine to rev more safely to exploit the greater performance potential of a 4-valve head. I guess a pushrod design would also not be ideal for this purpose either. Maybe some experienced engine tuners will chime in here.

Syd Mullarney produced a 4-valve head for the Manx, and Bob Newby raced the bike. He is of course known to Norton riders for his belt drive conversions. The legendary Joe Ryan Manx Norton, which was raced in Irish road races with such success in the 70s and 80s by Sam McClements, was reputed to be an ex-GP bike with a 4-valve head. The stewards ordered the bike to be stripped to measure the capacity after one race because the bike was so fast and Joe Ryan was seen covering the head in a towel as he removed it. I remember this bike embarrassing big Suzukis, Hondas and Tridents in open class road races and getting podiums before classic racing was established.

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Re: Commando Top Speed?

Postby Chris » Sun Jan 02, 2011 9:11 am

Hi
Piper 4 valve heads
Speak to Les Emery at fairspares.
On E Bay you will occasionally see him selling a 4 valve piston.
The head was developed by Pete Lovell (the man) as standard it did not add anything to a stock bike. After Petes work it added in all areas. However not enough for the money & imagine a breadbin (or a house brick) stuck on a set of Commando barrels & you will get an idea of what it looked like!
ie it was a test bed with no styling influence.
I dare say Les will sell you one.
all the best Chris
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Re: Commando Top Speed?

Postby Carbonfibre » Sun Jan 02, 2011 9:14 am

Its very easy to get an old motor to rev much faster, either by more efficient induction and exhaust systems, or by forced induction. However its even easier to get them to blow up, and this was something that was found to be the case time and time again, when old Brit twins were being used for drag racing back in the 1960s.

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Re: Commando Top Speed?

Postby jseng1 » Sun Jan 02, 2011 10:58 am

When the 4 valve head was tested way back it was supposed to put out 90 hsp and to have pulled the spokes out of the rear wheel - totaling the bike.

If anyone is interested in spending a fortune to have one made - give me a PM.
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