Commando Top Speed? (2010)

My old Norton Racing Motorcycles book says Phil Reed hit 155mph at Daytona in 1972.

Says with 9.5 compression, 32mm Amal GPs, "combat" specification cam, quotes 69 hp.

Wonder how many teeth countershaft sprocket or other gearing changes from stock to be able to hit this speed?

 

For an honest to gosh Norton Commando, that'd be Norman Hyde on a '72 John Player full faired special on an air port run way in French at over 170 mph. I lost my files on this and can't find juicy details on line so far. Here's some evidence and place to follow up for more.
http://www.saskma.com/content/view/175/61/

 

During prototype high-speed endurance testing at the Motor Industries Research Association banked tri-oval, we would run between 100 and 110 mph for 10 hours a day, including fuel stops and chain tightening exercises (we had the 1/4" chain initially). The two riders switched rides every time we gassed up. At one time we were running two bikes with three riders switching off between them.

We did have one spectacular engine destruction when the chain broke at full throttle on the top of the bankng. Luckily, the engine bits were mainly contained within the case and only the chain was left on the track. We later were able to find it and determine that the split liknk had failed.

It really got interesting for the rider (not me that day) when the Aston Martin that was on the track with us and running around 160, started catching up rather quickly!

 

I think the Factory naked HP850 ran over 140mph in the flying quarter to beat the Z900.

Cash

 

That factory "blueprinted" 850 that did the 142 mph was on an airstrip, and with different gearing did a 12.1 sec 1/4 mile. (Anything that can do 140 over a quarter has a LOT of mumbo ?). It had a 1/2 fairing on it for the 142 mph airstrip run ? (not sure about this bit)

The Factory put out tuning sheets specifying was was needed for this - the sheets were called Stage 1 and Stage II for an 850.
A 4S cam was at the heart of it.

A magazine article on the engine build (in Motorcycle Mechanics) mentioned that Dave Rawlings and his crew had access to all the factory parts - and could hunt for a pair of perfectly matched rods (weights, lengths etc), 4 identical cam followers, all cam lobes with identical degrees, etc etc etc.

Not beyond the average owner.
But perfection as only a factory bike can be....

 

P.S. I have a feeling that Norman Whites recent fully faired commando racers have clocked some very impressive speeds ?
Formerly an engine development engineer with NV, and then Honda Britain, he is currently engineering bikes including Nortons, somewhere near Thruxton.
I'm sure I've seen a clocked speed of +190 mph mentioned..... ?

Long way from being a standard road bike though.....

 

The Owners Manual or the Workshop Manual gave a chart of speed versus sprocket sizes versus rpm for the Commandos.

I think it was something like 110 mph for a 19 tooth gearbox sprocket at 7000 rpm.
And 122 mph for a 22 tooth sprocket.
On the Dunlop or Avons of the day (Rear 4.10 x 19).

7000 rpm was considered redline for a standard engine.
Although combats could see 8000 rpm in the lower gears ?

HTH

 

Gosh Frank, that's a lot of wind in the face flying all day on Cdo's!

Ms Peel- spiffed up Combat naked was geared high so only pulled 6000 in 4th to show 135 which was hard for me to believe until months of teasing sports biker to match me and report their speedo readings. Their speedo's read almost 140 because they are all set to read hi for speeding ticket legal reasons. Smiths speedo and drive in good function is very accurate. Peel pulled good up to 130 then took longer to creep up on 5 more mph. On slight down hill opens she'd show even faster but that's cheating so can't count it expect my glee. Peels engine was accidental set up going against standard mods to power, just to break in cam and rings, but boy howdy did it surpise me once time to see if it'd just blow up holding WOT. Don't know what next engine is worth with a bullet shaped big fairing.

 

I don't think a Commando with 32mm Amals and 9.5 compression will make 69 hp or go 155mph at Daytona. The Commando I won Daytona on in 2009 actually did make 69 hp at the rear wheel on the dyno and I was clocked at 129 mph by the speed gun there. If you have a big flat airstrip and super tall gearing you could go a lot faster of course.

 

I agree.
My race 750 has 36mm Amals 10.5 compression and an Axtell 5S cam. It makes 60bhp at the rear wheel. With the highest gearing I have it's supposed to be 132 MPH at 7000 and I've seen pretty close to 7000 in top which adds up with the above.

All this talk of 150MPH and even 170 I find very hard to believe. In an aerodynamics textbook I have it says that at 100 MPH if you want to go 5% faster, you need either 5% reduction in drag or 16% increase in power. Think about it, to get from 130MPH (which is a reasonable figure for 70bhp) to 170MPH would take a massive increase in horsepower which is simply not available from a Commando engine.

 

PommieJohn, do you have a full fairing on your racebike ?

The JPN Racers were quoting that their full fairing was worth about the equivalent of another 15 bhp over an unfaired bike.

And with about 80 bhp on tap, the 1973 JPN Racer at Daytona was pulling just over 165 mph on the speedgun, supposedly.

Like the old belt-drive sidevalve singles at Brooklands, there is a trick to diving off the banking to get a fast run down the straights. ??

I've worked with the speedgun crew on conrod straight at Bathurst, in 1981 the bikes in the Arai 500 were wheelying over the humps at just over 285 kh/hr. That sorts out who has their spring and damper rates set correctly. Not too many Nortons would have been competitive in those days though., although not by much really....

 

What is the highest speed a Norton Commando has been clocked at any drag strip or at the Salt flats? I mean a single engine bike no ultra fancy Streamliner, just any "regular" bike???

 

80bhp? Peter Williams in a chat I had with him in 1979/80, i.e. still pretty close to action, told me the best 750 engine they ever had on the testbed gave 74bhp AT THE CRANK (not the rear wheel!). Forget all the bulls**t you read from Crashcart and others. About as real as the bhp figures for the racing rotaries that were published.

Compare the 74bhp to the 65bhp a "Combat" supposedly had and you know what they really had- about 50 to 55.

With today's knowledge about combustion chambers, porting, and better camshafts- we use the PW3 normally- you can get better results.

 

Rohan,
I've found a photo copy of this article, bottom corner of each page gives the site http://www.classicmechanics.com. anyway to quote the article;

"At Elvington in 1974 when it (the HP Commando) clocked 145mph over the flying quarter mile." it was a yearly records event and Kawasaki were there with their Z1 ridden by a 6 stone Dutch 50cc champion Aalt Toersen the Z1 did 132mph. A photo taken on the day shows the Norton naked but fitted with clipons.

For the standing quarter; " it was regularly clocking quarter mile times of 11.8 seconds." Bloody quick or what

I've written on the photo copy August 2002 issue 178, but that might be a red herring. If anyone is interested I'll try and scan the article and post it.

Cash

 

Have a picture fo ' Motorcycle Mechancs ' or suchlike of the Gear Box Spocket of one of the Daytona bikes , a lot of teeth .
23 give you third about where top is on a 19 T . And a bit of ' letting in ' the clutch with a Combat Cam .
Surprisengly on the Std Cam its a lot more manadgeable , except perhaps in heavy traffic, stop and start.
Your lible to run somethng over . Saw a Honda 500or scrambler or similar ride onto a VW , looking over his shoulder as he gassed it .
VW stopped and he ended with the front wheel half way over the roof. ANYWAY .

Glen Simmons P.R. 5 speed aledgedly ran 160 mph timed , on methanol in N.Z. in 72 / 73 .

H.D. and Norton were alledged aroumd 158 mph around 72 , F-750 .
An ounce of handlings worth a pound of horsepower.
Then theres STREAMLINEING .
Walked into a bike shop around 94 , & saw a 74 F-750 Norton , - copy fairing , on a big kwikersaki ,
only took them twenty years to copy it , and get the frontal area down by minimising HIGHT .

Was a Cycle World artical of the F-750 machines , goinginto fronal areas etc. Sq. Ft. etc .

Pity I havnt got a scaner , or a computer . Wouldnt have one in the house . then theres the house !


Matt. :mrgreen:

 

Hey Matt, think of a digital camera as a scanner, it does the same thing but much faster. Even light should fall on your copy work from a 45' angle (a large window works well). If the page is double sided place a black card under the page you are coping and it should eliminate the print and images you can see through from the front side. Scanners allow you to adjust contrast etc before you scan but if you look after the lighting and over/under expose by a stop you can tweek it in photoshop quite nicely.

 

In 1972 Peter Williams was speedtrapped at the Highlande in the IOM at 148.8mph....but that was with the "69bhp at cramk" motor. A lot of the speed was down to aerodynamics, and with a little bit more power and much better aerodynamics (and still a 350lb bike) he was clocked at over 160 in 1973. This was about 10mph faster than the more powerful Tridents!

 

OK. I've trawled through the internet and found a load of road tests of bikes that include BHP and top speed and plotted them on a graph. These are all tested rather than claimed. They're all modern bikes but a mixture of unfaired and faired.
The top one is a Hayabusa the bottom one, some little 125, can't remember which, but they all seem to fit into a rough line.

The graph suggests that to get to 150 MPH you need around 100BHP. I know the JPNs had great aerodynamics and I'm prepared to believe they could get there, but 160MPH, or even 170MPH ? Look at the power that the modern bikes are producing to get there.

I seriously doubt a Commando could get to 160MPH

 

In the real world top speed is directly related to BHP at the real wheel, and has nothing much to do with BS factory figures or advertising features published in magazines. I would guess that road bikes with 45-50 bhp at the wheel, are going to have a to speed around 105-110 mph. Fully faired race bikes with maybe 65-70 bhp, are obviously going to be a lot quicker, and discounting the factory and magazine BS a good indication of this are the speed trap figures recorded at the IOM TT races and the MGP.

 

Here's the article on the HP 850 I hope it's readable.

Cash