2S Cam in standard 750

Cant ' edit ' it ; further thoughts -

Will pull from 11.000 , V delicate use of throttle from 800 . In city trafic , on 23 T it meant you allowed a car ahead to clear a length , or youd be on & off the clutch , getting under way . 2S .
Whereas std. cam it'd pull from 500 .

' pull ' in these cases meaning you didnt have to be overly attentive to the throttle . E G , if your boot slips in gravel & the bike starts falling so you declutch , on a 2S cam , things get demanding .
really wants the 21 Tooth , tho 19 if your a stop light hero would work well .

As In , below those rpm's , youve not got the clutch ' home ' . Dragging it led to gummed plates - so we decided ' letting it in ' gave the least wear . Judiciuos throttle , it is ' let in ' at those rpm's .
As in ' home ' , The S cam was docile , whereas the SS it took itself to 2200 / 2500 - or was on the overun . So ' coming in ' to lights , youd de clutch & get neutral early , rather than as you pulled up .
Beforehand , in fact .
So , if the light changed , youd select 2nd or first , as required . As past 1/4 throttle it wanted a clear battlefield ahead . Technically its a ' 2 stage ' cam , as they were called . So a differant riding tecnique
is required to suit . Country riding its not so demanding , except at garage forecourts & village intersections . Caution is indicted untill ' clear road ahead ' . So riding is not a casual occupation in suberbia .

Undivided attention , is the term . if youve not your wits about you you may end up witless , permanently . Space time continuum . The SPACE will tend to become extreemly limited , rather quickly indeed .

A race cam will work in any motor regardless of the compression ratio. The usual effect is a more distinct power-band which starts a bit higher. But because you often cannot raise the top of the power-band without changing the crank's balance factor, you often end up with lress versatility. The usual answer is close ratio gears. However close ratio gears will help any Commando to accelerate faster. So why fit a race cam ? A Manx cluster with a Commando 1st gear would not be difficult to use. - $700. When I first raced my bike, I tried to use a normal Norton gearbox - it was bloody hopeless - everything happened too slowly.
A lot depends on how you intend to use the bike.
When you ride a bike with a four speed gearbox, if the ratios are wide, you rely more on throttle response. When they are close, all you need to do on an upchange is ease the throttle to take the load off the gears, stand on the gear change and immediately get the throttle wide open again - without using the clutch. You will find the bike accelerates much faster than it will with standard ratios. With a Commando 1st and a Manx 2nd, there is a bigger gap, but you would get used to riding with it. With my bike I used the 4 manx ratios - it was a bit slow moving from a standstill. But with a standard Commando 1st gear, you can probably do 50 MPH, which is easily fast enough to pick-up the Manx 2nd gear, when you are in a hurry. I was too dim, so I bought 6 gears close ratio - I did not need to do that. I know a guy who races a Manx - he has 3 first gears - all the old Norton gears from early models, usually fit the Commando box.
One of my mates said ' if you have a torquey motor, you do not need a close ratio gearbox'. Lately he has been racing a Z900 Kawasaki in a different class to me, but I know how fast a Z900 is not, and where. Some guys have never really raced.
I never believed in my Seeley 850, but now I do. It surprised me. It is amazing what you can do with so little power.
My first race bike was extremely fast for a 500, but I could choose where I wanted to lose a race. It badly needed 6 gears. If I geared it low, I was likely to hit someone in a corner.
I do not think many people know how much the gearbox affects performance.
When you hot-up a Commando motor, you are playing with one hand tied behind your back. The rest of the bike slows it down.

I do not know why anyone would want a faster Commando for road use. I do not usually ride on public roads, because out of habit I always ride aggressively. When I drive a car, I just sit in the traffic and go through the motions. My car has 6 gears close ratio -it just cannot be used properly. I usually use the box as a 4 speeder. The car is a 2.5 litre Mazda 6. My wife likes to get it on the freeway, and accelerate up using all 6 gears and race-changing while she is doing it.

acotrel said:

I do not know why anyone would want a faster Commando for road use. I do not usually ride on public roads, because out of habit I always ride aggressively.

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Nothing wrong with riding a little aggressively away from the towns and cities here the USA. All one has to do is pay attention use common sense and avoid the POPO. A few close calls with oncoming traffic in tight blind corners and you would probably change your riding habit or die. Just saying

My 750 is probably a little quicker than a stock 750 Norton Commando, but it's not fast by any stretch of the imagination. It is about right for an old guy riding on the street.

With my hotrod Norton running the 2S cam and all the other work done to the motor, it's not about how fast it is on top end speed, it's the get up and go that is best, it's how quick it get going from taking off and getting through the rev line and gears, and how the motor breaths a lot better with a freer motor without over doing it, so much better than a stock motor, gives me a good rush and knowing my Norton can get up to the ton quickly if I want too.
A well-balanced motor, bigger cam, open ports, carbs jetted and tuned right, a big spark and open turned exhaust system make for a freer engine to breath fire and a head rush for the rider who knows how to ride it, it also makes it a bit better when running down low as well, but with any engine you learn not to labor it.
It's not all about how fast my Norton goes, that has nothing to do with it, even in my youth it was never about that but how it gets up there, from new my 850 Commando had restrictions with running but when I built the motor for the Featherbed frame was when I did the high-performance work to the motor and made it breath was when it woke up the motor, but a bigger cam will only work if you do the other work to your motor, you don't have to over do it to keep it reliable and useable at any part of the rev line, makes for a very fun bike to ride and makes it a bit more smoother as a well to ride.
I just love that get up and go and knowing I have it when I open that throttle.

Ashley

I can only judge from my own motor, but it seems to suggest that a standard Commando 850 engine is surprisingly good. I probably use it in a very different way. I use very high overall gearing with close ratio internal gears. I probably make better use of my motor's torque. With a race cam, it is usual to get a pleasant surge of power when the revs pass a threshold. But I mever notice that, because only when I am srtarting off, the revs are ever below 5000 RPM. The bit of the power band I use is between 5,500 RPM and 7000 RPM.
If I rode my bike on a public road, it would be too fast everywhere.
What you are dealing with when you use a 2S cam, is probably rthe difference between a race bike and a road bike.
I have never raced modern bikes, but most guys who do it, probably do not use race cams or racing gearboxes. The bikes are fast enough without resorting to that. The thing which slows them down a bit , is the exhaust systems - a modern 1000cc Suzuki with separate pipes with megaphones would be stupid.
It is very easy to build a motorcycle which would scare you shitless. My first race bike was built by my mate who used all the theories. After he crashed it at Bathurst, he did not race agan for 25 years. When I got it, I found out why he crashed. If you backed-off in a corner, you crashed. Below 6000 RPM the motor dropped dead, and the bike always went sideways if you slipped the clutch.
I do not know what cam is in my 850 motor - when I had it ground, the guy who did it, had been grinding bike cams for decades.
He worked for Eddie Thomas who sponsored Alan Moffat who became out top touring car racer. I am fairly certain, it has to be the cam which was used in the 650SS. There are no big bumps in the power delivery. From 5,500 to 7,000 it has tons of torque.

You mentioned a port job. My inlet ports are tapered from 34mm for about the first 15mm - after that they are 30mm. I would not go bigger. The main advantage of a Commando 850 motor is it's pulling power which compensates for poor throttle response, when you use close gear ratios. If you lose revs with a Commando engine while racing, you are stuffed, especially with a wide ratio box.

acotrel said:

I can only judge from my own motor, but it seems to suggest that a standard Commando 850 engine is surprisingly good. I probably use it in a very different way. I use very high overall gearing with close ratio internal gears. I probably make better use of my motor's torque. With a race cam, it is usual to get a pleasant surge of power when the revs pass a threshold. But I mever notice that, because only when I am srtarting off, the revs are ever below 5000 RPM. The bit of the power band I use is between 5,500 RPM and 7000 RPM.
If I rode my bike on a public road, it would be too fast everywhere.
What you are dealing with when you use a 2S cam, is probably rthe difference between a race bike and a road bike.
I have never raced modern bikes, but most guys who do it, probably do not use race cams or racing gearboxes. The bikes are fast enough without resorting to that. The thing which slows them down a bit , is the exhaust systems - a modern 1000cc Suzuki with separate pipes with megaphones would be stupid.
It is very easy to build a motorcycle which would scare you shitless. My first race bike was built by my mate who used all the theories. After he crashed it at Bathurst, he did not race agan for 25 years. When I got it, I found out why he crashed. If you backed-off in a corner, you crashed. Below 6000 RPM the motor dropped dead, and the bike always went sideways if you slipped the clutch.
I do not know what cam is in my 850 motor - when I had it ground, the guy who did it, had been grinding bike cams for decades.
He worked for Eddie Thomas who sponsored Alan Moffat who became out top touring car racer. I am fairly certain, it has to be the cam which was used in the 650SS. There are no big bumps in the power delivery. From 5,500 to 7,000 it has tons of torque.

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Well I'm glad we've got that straightened out