Commando cam

I have been told that a standard Commando cam is the same profile as the early Dommie SS cam profile, well on my work bench at the moment is my project bike motor, a 1960 650 Manxman motor, I have brought a brand new SS cam for it as I am building it up as a cafe racer as well on my bench I have a mates Commando motor ready to be put back together, so I decided to go and put my verniers on the Dommie SS cam lobs, then put the verniers on the standard Commando cam lobs, the Dommie SS cam lobs are a lot bigger than the standard Commando lobs, I will tomorrow measure the standard Dommie cam and see if its the same size as the Commando.

I only took a quick look at it tonight 11PM so tomorrow I will measure all 3 cams and get the right measurements (Standard Dommie cam, Dommie SS cam and standard Commando cam) and compare all measurements, when I built up my 850 Featherbed I got my standard cam built up to a SS cam profile and know it revs a lot harder than the old standard cam.

Ashley

Never heard of a "domi"SS cam. :?:

I finally accept the "common" definition of DOMI as all twins from 1949 through 1968 but not really including commando.
650SS yes.
Don't have all the data on a 88SS or 99SS cams, only what I have read in glossy picture books.
I tested a model 18 ( 650SS/USA Manxman) and it shows a profile the same as a 06-1084
combat 2S yes

You can buy an aftermarket combat 2S grind on a 18 or 20M core (I have one from Norvil) . 2S is NOT used in any original 500, 600, 650 SS bike.

dynodave said:

I tested a model 18 ( 650SS/USA Manxman) and it shows a profile the same as a 06-1084
combat 2S yes

You can buy an aftermarket combat 2S grind on a 18 or 20M core (I have one from Norvil) . 2S is NOT used in any original 500, 600, 650 SS bike.

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Aren't those 2 statements contradictory ??

So does a 650SS cam have an SS grind, or a 2S grind ????
Are you saying the first Commando used a milder cam than the SS dommies, or not ?

Anyone got the part numbers of all the cams used in the early 1960s. ?
The 21225 is listed for the 88, 99 Std and 99 Deluxe (enclosed model).
The 22729 is listed for the 650 Std and Deluxe.
What did the SS models use ?
What did the Atlas use ?
My parts lists don't go far enough...

P.S. It is a little misleading to call any Manxman a 1960 Model ?
They were announced as a 1961 model, and were assembled from late 1960.
Anything Built from Sept was a next years model in the british motorcycle industry...

Well the 650 Manxman first came out in 1960 and went to 1961 then after that they became the 650SS, I don't know if the 650SS had the SS cam or just a standard cam, Manxman were the begining of the first Slim line Featherbed frames and came out with a blue frame and bule paint job, my frame was blue but well worn and is now painted black, my motor isn't the orginal motor for my frame as the frame and motor numbers are about 79 out but my frame would have been one of the first slimline frames as has very low numbers on it, the number on my frame is 18 95000. This bike was a ex race bike from Mike Farrell and has race history.

My first workshop manual I brought 35 years ago has at the back of the book that has a section in it on High Performance up grades to Commando engines and and up grades to handling, it has a high perfomance stage one and stage two engine build up, the stage one for road use and its tells what cam to put in and reconmends a SS cam upgrade, the stage two is for high performance race engines and reconmends a SSS cam, I built my 850 to the stage one and did the work the way the high perfomance section recomened, it tells you all that is needed to build a high performane motor, from carbies to head work, pistons etc etc and I can tell you this my 850 is a very fast and powerfull engine and has not let me down in 33 years of being built to stage one set up, I was 21 years old when I built this bike up and the motor has only been rebuilt fully 2 times in that 33 years and well over 140,000 miles.

Ashley

The FACTORY performance sheets I got for my 850 some years back details fitting a 4S cam for performance work.
And going the whole 850 Combat path, like Mr Poore wanted to build but noise regs wouldn't allow.
Never did it though, just thought about it....

The Manxman was announced as a 1961 model, although the very first were built in late 1960.
Nortons always said that anything built from Sept was a next years model.
They shut down for the August hols so the factory could be rejigged for the new models.

ashman said:

My first workshop manual I brought 35 years ago has at the back of the book that has a section in it on High Performance up grades to Commando engines and and up grades to handling, it has a high perfomance stage one and stage two engine build up, the stage one for road use and its tells what cam to put in and reconmends a SS cam upgrade,

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If you go to a Commando Parts Book and look for an 'SS Cam' upgrade, where is it listed and what is the part number. ?
And whose description/naming is that.

The Combat 750 got a 2S cam, and there were later 3S, 4S and 7S cams.
Nothing SS listed that I can see...

The "SS" of old became the 1s of new. Same grind.

Didn't the 1S become the standard cam that went into Commandos though ?

Maybe the SS cam is the 2S cam and the SSS cam is the 3S cam and so on, just in my book it referr to them as SS and SSS no big deal its just the way they wrote it as thats, remember it is over 38 years ago and they do change reffrance to things over time, and yes they did come out in end of 1960 but was the 1961 model as it was only porduce for one year before the 650SS models, the orginal Manxman only had one carbie but my motor was set up for racing and had 2 side bowl carbies, but the only thing that was missing when I brought the Manxman was the head, I brought it in boxes and lose parts and because the head was missing I got the bike really cheap, it has alloy wheels, central oil tank so not many oginal parts, thats why I am building it as a cafe build and it has a brand new Alloy fuel tank,

The person I brought it off of brought it off Mike Farrell over 19 years ago and pulled it down to rebuild it but he didn't know what he was doing and it just sat in his shed for those 19 years, but the worst thing he did was not to mark all the parts to know which side the rods and pistons went and the only thing that had signs of wear were the slipper bearing on the rods and his place was where the head went missing, I payed $1000 all up and I got another head with new valves for $400, it also has a compertion race maggie and are woth a lot of money here in Australia, so I think I have done well.

Ashley

Rohan said:

Didn't the 1S become the standard cam that went into Commandos though ?

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That's my assumption.

ashman said:

not to mark all the parts to know which side the rods and pistons went

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There is only one way the pistons can go in there, being handed - and if the rods are attached that settles that !?

But we diverge....

ashman said:

Maybe the SS cam is the 2S cam and the SSS cam is the 3S cam and so on, Ashley

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No, I'm sure the ss was the race cam way back when but worked so well that they utilize the grind as the standard for Commandos

Thats exactly what I said - that started this.

DynoDave seems to be denying that (above). ?
Although the words are less than totally clear...

Its not hard to work out that the SS cams are 2S cam and so on its the way refreance have changed over the years, but the 2S cam profile is bigger than the standard Commando cam profile, I know my New Commando when I brought it in 1976 only reved out to 6,500 RPMs, but with the SS cam (2S cam) my motor will run freely well over 7,500 RPMs or more if you let it and has no problems getting to 130 mph with standard gearing, but I am older and more wiser now, but it gets over the ton very quick and in the high performance section it tells you to watch the revs as it will run freely and won't stop till something goes bang.

Ashley

Norton had SS cams for dommies (and a few versions of std cams), and later had 2S cams for Commandos.
So its not at all obvious that these are the same.
In fact, they are most definitely not the same.
They appear differently in the parts lists....

This is turning into a good talk and we all have our opinions, we all could be right and we all coudl be wrong thats the good thing about this froum, we are all open to talk about it, I am glad that I started this off and have no problems with everones opinions and ideas, its the way these forum should work and how we make good friendships with each other over time and it wouldn't be fun if we all agreed with each other.

Ashley

Pete I have worked out which piston is left and right as thats not hard and as for the rods they were off the crank but had the slipper bearings still on the rods, one slipper was worn down to the bronze and the other only has slite wear showing so I think the worn one would be the drive side of the carnk and will be the way it goes back on when ready, the only thing I have to do now is replace the Supa Blend main bearings as I used my new ones in my mates 750 rebuild.

Ashley

Rohan said:

Norton had SS cams for dommies (and a few versions of std cams), and later had 2S cams for Commandos.
So its not at all obvious that these are the same.
In fact, they are most definitely not the same.
They appear differently in the parts lists....

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I think the confusion is that they are not the same cam, but the same grind/profile on a new cam hence the different part numbers etc.

ashman said:

This is turning into a good talk and we all have our opinions, we all could be right and we all coudl be wrong thats the good thing about this froum, we are all open to talk about it, I am glad that I started this off and have no problems with everones opinions and ideas, its the way these forum should work and how we make good friendships with each other over time and it wouldn't be fun if we all agreed with each other.

Ashley

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Well, what else do we have to do on a Friday night but talk cams, so please allow me to add one more cam opinion.

Mr Comnoz informed me some time ago that the SS cam was an Atlas Dominator performance cam (and I believe won the Thruxton Race in 1961 and 1962?) and thereafter became the standard 1S cam in Commandos. Thus the SS = 1S Commando cam. The Combat Commando used the 2S cam, which is not to be confused with the SS = 1S cam.

The data on David Comeau's website appear to dovetail nicely with the above description where he has a cam from a model 88, which is a very low lift cam at ~ 0.300", so definitely not an SS = 1S or a 2S. There are 2 different 650 SS cam profiles shown, both of which have constant velocity opening/closing ramps, equal IN and EX lift of ~ 0.330" and crossover at a lift of ~ 0.125", all of which is perfectly consistent with the subject parameters associated with a Commando 1S cam. There is also a 2S cam profile pictured that exhibits the unusual flat velocity opening /closing ramp and the staggered IN/EX lifts of 0.390 and 0.346" respectively. In light of the foregoing it appears the SS profile could not be the 2S profile.

The plots referred to above on Davids site are found in the section at the top of the page titled "Norton", and in the order discussed are files - cam140.gif, cam110.gif, cam 110a.gif, and cam 120.gif.

http://atlanticgreen.com/camsurvey.htm

That all sounds right, in my old manual in the high perfomance section it referr the cam as a SS up from the standard cam for the road version (stage1) but I think it would be the 2S cam profile as it is a lot bigger than the standard Commando profile, I have never come across another workshop manual with the high performance section in it, its a old Hannes manual that I brought over 36 years ago.

Ashley