certified quarter-mile time.

Matt Spencer said:
If a XS 11 did it with 1000 , a Norton at two thirds the weight would do it @ 60 horse with a Slick aft . ( not ' oil ' slick ! :lol: )
Oops . 100 .

Percentages apply , amongst other things , such as rider Wt & if he had breakfast .17T countershaft sprocket , redline at gate in top . Plus 100 Octane pump gas , 5 star in 1970 so 10.5 : 1 C.R. entirely workable .

If that didnt work , dropping a stick of gelignite behind him on the line , would have him off like a cut cat . :mrgreen:
Click to expand...


I see you are not that familiar with drag racing! In the UK during the 70s a guy who worked for the Norton factory was racing a "street" Commando, fitted with full race motor quite close to the ones that were used in the magazine "test" machines. Guys name was Dave Rawlins, and to tell you the truth I cant remember him making an awful lot of 10 second runs, even though he was a pretty good rider, on what was ijn effect a reasonably trick factory bike.
 
Indeed . Im still trying to find a copy of the last stage of development , where he ran Norvil Type ( reangled Intake Valve )
Head , with the 36 mm Amals and changed to a Road Race Dunlop on the 18 in Rear , to get to 11.5 or 10.5 .

Unfortunately ' the works ' in any organisation occasionally comes in for a rude shock when the privateers have brighter ideas
The Jap ' looseing face ' usually has them confined to Coventry , if works supported .

A one pice steel crank in a Commando / 750 , and Ex Offenhauser or whatever odds and ends could well see that time
with the lowered frame , its feasable .

The standard Yankee ' Altered ' set up was struts , ground level engine cradle , and the stauchions pushed up in clamps .

Even on Kawasakis ! :lol:

They didnt suffer the budgetray constraints of Old Blighty and the Colonies , with the engineering resouces and clean sheet of paper approach , often radical reconfigurations of heads , valve train , porting etc are instigated .
Particularly in theres a rather large machine shop adjacent with rather large equipment and rather large pieces of metal .

A Norton Crank out of one piece high grade alloy steel , with end / oilway drillings not exceeding 1/4 in , would be
significantly more durable than the olde cast sludge trap big end type apperatus .
 
Murray wrote Sadly, Cycle Magazine did not maintain high standards and by the 1973 article, “Superbikes 1973” was claiming the “Combat” gave 12.896 and the Trident 12.718. It obviously was not a Combat at all if it ran two tenths slower than Cycle magazine’s own previous runs with the standard model."

Maybe you are expecting too much from the poor old Combat. A skim off the head can only do so much, especially if the port alterations are done badly.
According to Dave Comeau, the Norton Head Guru (Are you here Dave?) the Combat heads did not have great porting jobs.
Good porting came on the later heads.

"The 71/72 head. This would be the 2nd series of commando head,. as a standard 71and 72 small port they have original port size of 28.5mm. In 72 the head would be marked with a "C" in the center top of the head to indicate the combat conversion was done. The combat RH3 was cut .042" to raise the compression. It had a 32 mm porting job. It appears the factory learned more about the porting business as time went on. First hand inspection of several "combat" porting jobs show how crudely (bad) they were done. Big.... yes. By today's standards these heads have been ruined. The "BIRCO" on the right and the casting number faintly visible on the left side are negatives (depressions in the surface)."

and

"A 73&75 RH4 850 32 mm port head. The porting job out to 32 mm seems to have improved somewhat over the combat. The 850 head types are marked above the right hand exhaust rocker cover. They show a much bigger head gasket pattern compared to all the earlier head styles."
 
Id had the tapered type port , 30 opened to 32 at the head face . Im thinking the coustom manifolds , the ridius flowing
from tangental at the head face , mustve been resonsable for some of its efficency . Alledgedly semi ' Mk III ' type which
was said to be better low end and flexibility without impedeing flow up top.Theres a discernable kink in the stock set up .
( Id asked for parrallel 32 ' Combat ' , on reciept it wasnt , but the outfit got ' all ours done like that ' . Had just read the
' alledgedly ' on the Mk II type so thought F it , its done ( to suit carbs ) SO thered be ' a few ' heads in N.Z. to this spec ,
as they had them ' All of them are like that ' if converted to 32 by universal in Auck. around 1980 )

Pig off the line with the 23 Tooth , wanted sliding till 1500 or thereabouts if in a hurry , with the 2S cam . But retrofitting
a S cam got a seamless take off and on through the entire rpm range .Not quite the 'G's at higher rpms unfortunately .

Regretted never fitting a ' Combat ' head I later found . Slightly messed with by the look ,was near 33 mm parrallel intake bore . Saw no irregular shapes to the curves / intersections . The Old ' Garden Hose ' flat out flow testing at various lifts
generally saw the discharge at the head face pushing out in an extended cone right central to cylinder placement .
Would have to assume it wouldve picked up some horse power , albeit at the expense of bottom end .

With the 2S it had stutter ( if there ) at 2.200 / 2.300 . Depending on the approach , 3.000 to 3.500 was ' on the cam .
But definately , by 4.000 there was no question as to if it was ' in the powerband ' .

Just a few random thoughts for a comparison .Wouldve benefitted from a bit of weight of the flywheel for responce then .
 
Matt Spencer said:
Id had the tapered type port , 30 opened to 32 at the head face . Im thinking the coustom manifolds , the ridius flowing
from tangental at the head face , mustve been resonsable for some of its efficency . Alledgedly semi ' Mk III ' type which
was said to be better low end and flexibility without impedeing flow up top.Theres a discernable kink in the stock set up .
( Id asked for parrallel 32 ' Combat ' , on reciept it wasnt , but the outfit got ' all ours done like that ' . Had just read the
' alledgedly ' on the Mk II type so thought F it , its done ( to suit carbs ) SO thered be ' a few ' heads in N.Z. to this spec ,
as they had them ' All of them are like that ' if converted to 32 by universal in Auck. around 1980 )

Pig off the line with the 23 Tooth , wanted sliding till 1500 or thereabouts if in a hurry , with the 2S cam . But retrofitting
a S cam got a seamless take off and on through the entire rpm range .Not quite the 'G's at higher rpms unfortunately .

Regretted never fitting a ' Combat ' head I later found . Slightly messed with by the look ,was near 33 mm parrallel intake bore . Saw no irregular shapes to the curves / intersections . The Old ' Garden Hose ' flat out flow testing at various lifts
generally saw the discharge at the head face pushing out in an extended cone right central to cylinder placement .
Would have to assume it wouldve picked up some horse power , albeit at the expense of bottom end .

With the 2S it had stutter ( if there ) at 2.200 / 2.300 . Depending on the approach , 3.000 to 3.500 was ' on the cam .
But definately , by 4.000 there was no question as to if it was ' in the powerband ' .

Just a few random thoughts for a comparison .Wouldve benefitted from a bit of weight of the flywheel for responce then .
Click to expand...

One of the old style "tuning" myths was that bigger ports and longer duration cams made for a faster bike. While these changes in combination with higher compression would certainly mean more power at high rpm, bikes would often have less power mid range, with the effect being they became more difficult to ride, and would in most cases be slower in real world conditions.
 
:? The one I was familiar with had all its engine lugs fail , when it slid out on a oily city road at night in winter and put itself into a curb at 45 mph , down a hill . :( Driver was indifferant to its demise .
He'd raced it several times at bay park . Redline around 10.000 / 10.500 . Running 1100 it would stay with the quickers GSXs , but then the Katanas came out . . .
( blow an alternator doing 11000 , he did three before he decided it was to pricey . you didnt get them ' in the corn flakes ' .

as a person of Nautical lineage , I consider anything less than a KILOMETER sprint to be not indicative of a machines performance or durability . Careless indeed to blow one in a quater mile , a bit of fun ,
but Solo ' sprints ' , youre raceing no one but youreself . Depends on who youre trying to prove things to , if anyone .

The latter Jap afficianado ran one pommy bike , a 73 650 Bonneville . " Better road holding than the Japs , breaks cam followers at 8.500 , itll keep upo with any of them , but I did the cam followers three times doing it ". He got A Bevel Duke , these days . Professional Truck Mechanic , manadgement nowadays .

I got a Suzuki as TRANSPORT . HOPELESS . Got a triumph 650 , recomended by halfwits ( that Machine ) as ' a good bike ' . 18 owners , Er Not Quite . However , Overhauled it was dependable , developed as things gave out ( 20 yr old parts ) it was not troubled by any ' opposition ' at the lights . Id put it down to the characteristics of the clutch , with the cork plates ( more expensive to make ) superb ' feedback ' , grip , &
progression .

Both That and the Norton were four speed , a XS 1100 or anything , has ' speed range ' limitations with inadequte ratios . 5 speed were available . At a Price . But niether was a ' Cheap Motorcycle ' so the price
was comesurate .

Having tried motorcycles , I almost got a car , The Newlynn races to a outside observor were demonstrative of the Machines Available . The thing I was most impressed by , was when the sidecar outfit ( a kneeler ) left the road , It went through the Timber panel between the concrette pillars in a fence / wall , and noone was insufferably injured. Just a Few Bruises .

At that Era , f someone had a unlimited budget , A Vincent still reigned supeme , If run . particularrly in Speedway Sidechair .When one was running . Norvins obviously road raceing .
Bill Whites Velo MT 500 , 5001 had still in 1970 , if run , blown off all comers . ( Perry being one of many top ' piolots ' ). When Haldane got his TZ 750 that was regarded for maybe 20 years , as ' the fastest ' bike in the country .

Attending the Stret Races in 1976 with no ' Bone to pick ' , one was merely observeing the operating characteristics of the machines .

Obtaining a Commando , and haveing met Commando Riders , Id think " allways tell the Truth , And Fear No One ' , would sum up the majority then . Hoodlums and incompetants seldom went near the things till the 80s , when the situation deteriorated significantly , and even a Ducati wasnt immune to theft .

New Zealand had long regarded competant mechanics at their worth . And most considered the rreliability of the machine a product of its riders competance and ability and the mechanics thoroughness .

Not neccesarilly easy things to find . Sure the japs made good engines , but that was about as far as it went , before 1980 . You took your chances when you made youre choice , whatever you got .
Most people had enough brains not to ride a motorcycle into the ground . However a few took delight in it . There were many hard ridden machines of all breeds about , few had faultless reputations then .

The Landlords Son Today , I met . On his Honda 1000 wotsit ( Fireblade ). ' Gravel roads ' ? " No " , same old same old . Ce la Vie .
 
My biggest speed power surprise was putting the stock small port head on an other wise all Combat engine, WhooWee! but needs the exhaust tuned to match or was just about same as hogged out ports CHO head. On Ms Peel I'm hoping the big port CHO will act like small ports on a 920 up grade. My testing Combats reveals a nice increase in pull power after 4000/4500 but a 3rd piston power kicks in after 6800 if ya harden your heart to let er rip off another 1000 rpm above that. Then frying pan iron fly wheel and valve float can kick in too.
 
What seems to work very well is smaller ports, but larger valves. This speeds up gas-flow and provides increased torque, and there is no need for costly "porting" which always appears to work better on a flow bench, than on a bike being used on the road.
 
Hey Matt, I got your PM re Egli papers and tried to respond but the reply seems to stick in the outbox.

Did you get the reply?

thanks
Glen
 
Carbonfibre said:
I see you are not that familiar with drag racing! In the UK during the 70s a guy who worked for the Norton factory was racing a "street" Commando, fitted with full race motor quite close to the ones that were used in the magazine "test" machines. Guys name was Dave Rawlins, and to tell you the truth I cant remember him making an awful lot of 10 second runs, even though he was a pretty good rider, on what was ijn effect a reasonably trick factory bike.
Click to expand...


Until Dave Rawlins name was mentioned here, you'd not even heard of him. !!
You said Nortons had never even been to a drag strip.

Like a candle in the wind....

P.S. As far as is known, that engine was a one off, the press didn't get any to test.
But all the bits and advice were available, for owners to do it themselves.
 
worntorn said:
Hey Matt, I got your PM re Egli papers and tried to respond but the reply seems to stick in the outbox.

Did you get the reply?

thanks
Glen
Click to expand...


Goddit . The photocopiers a tength the price of the scanner . I just progressing ? from smoke signals and telepathy ,
will chuckem in an envelope with a stamp on it & youre address . cheers

One pic has ' Fritz Pier ' same as Egli Commando position . :|
 
Carbonfibre said:
What seems to work very well is smaller ports, but larger valves. This speeds up gas-flow and provides increased torque, and there is no need for costly "porting" which always appears to work better on a flow bench, than on a bike being used on the road.
Click to expand...

relitite terms , of course

This is something like what we used on the Bonneville . 8 stud . 1 7/16 & 1 9 /16 ( 73 750 ) valves , work done by the best headman in the country , at his leisure , involveing then evolveing theory and ' one of ours '.Cork clutch plates gave
superb take up , combined with tuned exhaust 12.5 is realistic on stock ( 24 T engine ) gearing .

However , for the Land Speed Recoed , big ports may be usefull . Sustained maximum rpm opperation is not the same thing as a flexable power band .
WE'LL HAVE BOTH , Thankyou . ( hence the 4 Valve progrssive twin throat blah blah line of thought . )
 
To get full range power band for standing start tire burn to top end rubber squealing I'm going with a big block down low gruntter with smallish ports and valves and when it gets into flow choking rpm flows the Drouin will have already made up for it and then some. Its not the way to make maxium power just a way to get faster rising torque curve all the way to redline. To ride the loose stuff with purpose requires staying in tire spin and drift to one degree or another. On Pavement its way easier to control the skiing but needs more power to stay loose for max grip.

I want to break 0.999 sec 1/4's on a Commando, will I ?
Online calc are fun to plug in mass, power needed for Et's and mph.
For instance a 500 lb pilot bike with 130 rwhp implies 9.1 sec.
If can hook up the power of course and not flip upside down backwards
http://www.race-cars.net/calculators/et_calculator.html
 
Rohan said:
Carbonfibre said:
I see you are not that familiar with drag racing! In the UK during the 70s a guy who worked for the Norton factory was racing a "street" Commando, fitted with full race motor quite close to the ones that were used in the magazine "test" machines. Guys name was Dave Rawlins, and to tell you the truth I cant remember him making an awful lot of 10 second runs, even though he was a pretty good rider, on what was ijn effect a reasonably trick factory bike.
Click to expand...


Until Dave Rawlins name was mentioned here, you'd not even heard of him. !!
You said Nortons had never even been to a drag strip.

Like a candle in the wind....

P.S. As far as is known, that engine was a one off, the press didn't get any to test.
But all the bits and advice were available, for owners to do it themselves.
Click to expand...


I have seen Dave racing in the past, and unlike most riding dinos he was quite impressive, but gave up riding when it became clear that his dino was no much for Z1's in the street class.
 
Matt Spencer said:
Carbonfibre said:
What seems to work very well is smaller ports, but larger valves. This speeds up gas-flow and provides increased torque, and there is no need for costly "porting" which always appears to work better on a flow bench, than on a bike being used on the road.
Click to expand...

relitite terms , of course

This is something like what we used on the Bonneville . 8 stud . 1 7/16 & 1 9 /16 ( 73 750 ) valves , work done by the best headman in the country , at his leisure , involveing then evolveing theory and ' one of ours '.Cork clutch plates gave
superb take up , combined with tuned exhaust 12.5 is realistic on stock ( 24 T engine ) gearing .

However , for the Land Speed Recoed , big ports may be usefull . Sustained maximum rpm opperation is not the same thing as a flexable power band .
WE'LL HAVE BOTH , Thankyou . ( hence the 4 Valve progrssive twin throat blah blah line of thought . )
Click to expand...


4 valve heads work far better for road and race use, and are something that were first used back in the 30s on Rudge single cylinder racers.
 
4 valve heads work far better for road and race use, and are something that were first used back in the 30s on Rudge single cylinder racers.[/quote]

That is in fact a " RADIAL " valve Head . The Four Valve was actually first used on the 1`908 Peugeot twin cylinder motorcycle , a double overhad Cam.
 
Matt Spencer said:
4 valve heads work far better for road and race use, and are something that were first used back in the 30s on Rudge single cylinder racers.
Click to expand...

That is in fact a " RADIAL " valve Head . The Four Valve was actually first used on the 1`908 Peugeot twin cylinder motorcycle , a double overhad Cam.[/quote]


How many valves did this "Radial" head have Matt, and what was the first Rudge model that had them fitted called?
 
You must log in or register to reply here.
Back
Top