Camshaft choice - especially 2S

Please can you discuss the merits and dissavantages of the 2S cam here, Please feel free to offer advice on all other cams and argue between yourselves so that you don't need to do so in other un related posts!

The board has an 'Ignore' feature that you add usernames too, then you do not see their posts. Thread hijacking is just normal forum behaviour and not going to stop. Take a step back and use the tools and your own filter of just ignoring unrelated posts.

Posting on a forum is like shouting out a question in a pub, you cannot decide what the answers will be or who answers without starting a fight. So just ignore what you don't like and thank the few answers that are on topic and useful.

The ignore feature is a blessing. I'm very happy that others use it on my name. That way I don't have to listen to their expert my way or the highway responses.

But you may block someone who this time does have something to say about the PO subject. If only people had a little restraint for the need to tell us thier opinion about something that has no relation to the question being asked - that sounds like this forum has a high percentage of politicians following it!

kommando said:

The board has an 'Ignore' feature that you add usernames too, then you do not see their posts. Thread hijacking is just normal forum behaviour and not going to stop. Take a step back and use the tools and your own filter of just ignoring unrelated posts.

Posting on a forum is like shouting out a question in a pub, you cannot decide what the answers will be or who answers without starting a fight. So just ignore what you don't like and thank the few answers that are on topic and useful.

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Bloody hell - what pubs do you frequent? a retorical question as I don't want to go off topic!

Nourish said:

But you may block someone who this time does have something to say about the PO subject. If only people had a little restraint for the need to tell us thier opinion about something that has no relation to the question being asked - that sounds like this forum has a high percentage of politicians following it!

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Forum subjects go off on a tangent and get detailed sometimes
It's the same in the real world
How many times have you had a conversation with someone and it stays on point?
That may well happen in a work environment
But I doubt it would in a pub environment with many people in attendance
Just don't worry about it ,it takes seconds to read someones reply and if don't like it or agree with it there's no harm
Just sort the wheat from the chaff as you go

Sometimes there is good info in those tangential conversations.

Glen

worntorn said:

Sometimes there is good info in those tangential conversations.

Glen

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Yes of course there is but frustrating when everyone else has ignored you - if you were in a pub you'd get up and put your coat on!

I've probably said this here before... There's at least 2 purposes that people have when they post in the forum.

1) One is for seeking information. Granted, as John said you can only ask the question, not decide who answers or what answers you get. Sometimes you don't get the answers you need...

2) People posting for entertainment. Those are fine to post on their own. Most of us enjoy a laugh..

The problem arises when an Original poster needs some help or advise and the hijacker turns the OP's thread into a him telling stories about "the gravel" or "running methanol" or any of the other entertaining stories that can hijack a thread which was started to get some information help..... It sucks! When I first found this place and started a thread or two looking for some opinions, I had a few of my information threads hijacked by a proficient story teller and my request for feedback on my topic was turned into story telling time.... more than once or twice.. I've found that once your serious topic becomes storytelling time, it cancels the information thread... and the thread continues as people respond to the hijack, not the OP's topic.

Just my observation, so I'm sharing it. I like threads that are entertaining too, but I'm careful to try not to derail information threads with my bullshit.....

On topcs such as cam choice , exhaust systems and compression ratio, I read every post very carefully. I cannot afford to buy a large variety of camshafts and exhaust systems and try them. Even Hobot was actually capable of making some sense.
Recently somebody commented on Joe Craig's tuning philosophy, it answered a question I had long had, as to why Manx Nortons had sodium-cooled exhaust valves.

Nourish said:

Please can you discuss the merits and dissavantages of the 2S cam here, Please feel free to offer advice on all other cams and argue between yourselves so that you don't need to do so in other un related posts!

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I used a cam that has two SS's stamped on one of the lobes. It was purchased from Raber's Parts Mart as a 2S cam, or an SS cam. I can't remember exactly. It is not as friendly a street cam as a stock cam would be with higher gearing. I did use the SS cam in a 750 engine with higher gearing, but I didn't have any issues riding slow if I had to. Where it wasn't so great is riding around in 25MPH zones in town in 3rd gear to keep the exhaust note lower and trying to use 3rd gear when a hill came up. Then I had to downshift to 2nd where with lower gearing I wouldn't have to. That said the cam was nowhere near the optimal operating range at 25MPH in 3rd gear regardless of the gearing.

In the optimal operating RPM range which is probably 4000 to 6300 RPM it was fun on the right kind of road. The USA is not like the UK though. There are plenty of places where that optimal RPM range can be used.

I did not use Amals with the SS cam for long, but it worked OK with the 930's. It worked a lot better with 34mm carburetion and later some 35mm carburetion. Head was also mildly ported and I have a one off 2 into 1 exhaust.

Not using the SS in that engine anymore, because I wanted to see how a JSM JS2 cam works.... Might be heading off topic so the end.

acotrel said:

On topcs such as cam choice , exhaust systems and compression ratio, I read every post very carefully. I cannot afford to buy a large variety of camshafts and exhaust systems and try them. Even Hobot was actually capable of making some sense.
Recently somebody commented on Joe Craig's tuning philosophy, it answered a question I had long had, as to why Manx Nortons had sodium-cooled exhaust valves.

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Tell us more.
What do you understand the reason for "sodium-cooled" exhaust valves is?

I might as well add the stuff that has already been mentioned about 2S cams. By the way, bits and pieces of 2S cam information have been mentioned in the distant pass. The Search function although a bit tedious to use can answer a lot of questions you may have.

The Combat spec 2S cam can be a little rough on the valve train. However, I personally don't think it is worth worrying about. Change oil and oil filter frequently and use a quality oil. The 2S also makes the engine sound a bit noisy because it uses a greater valve lash spec than a stock cam and has steep ramps. I liked the way the 2S worked in my engine, but I know a lot of people would have no use for it at all.

Schwany said:

I did not use Amals with the SS cam for long, but it worked OK with the 930's. It worked a lot better with 34mm carburetion and later some 35mm carburetion. Head was also mildly ported and I have a one off 2 into 1 exhaust.

Not using the SS in that engine anymore, because I wanted to see how a JSM JS2 cam works.... Might be heading off topic so the end.

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How does the JS2 compare to the SS? I love my SS, especially over 4k, but if there's even a better cam....

And you may be onto something on larger carbs. I have 32 Mikunis and i can't get them dialed in. They are running rich and fouling the plugs, but the bike doesn't like less fuel so i'm thinking it needs more air.

concours said:

Tell us more.
What do you understand the reason for "sodium-cooled" exhaust valves is?

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The hot exhaust valve was apparently the source of detonation when a Manx engine is used with very lean carburation. When I was a kid, some of my mates raced Manxes. An exhaust valve cost 15 pounds ans a piston cost 30 pounds. At that time I was earning about 20 pounds per week. I thought my mates were insane. I could not see the reason for sodiem-cooled exhaust valves. But in our days, most people raced using methanol, so detonation was not a problem. In the UK and America these days, most guys probably race Commandos using petrol, so the detonation problem is probably still there.
I always believed that If I lowered the needle in the carb until I got the miss, then raised it one notch, that was lean enough. However it is more subtle than that.
Cricket is a Pommie game. Tuning a Manx Norton to go fast using petrol is probably similar to that. - You would need the patience of Jobe.

More radical cam timings often give a more pronounced power band. For an adrenalin rush, that is good. But not good when you need smooth power delivery, because you are tyre-dependent. A bike with a bump in it's power delivery is not good in the rain. Or in a very fast corner at high speed. You do not often see guys who ride two-strokes power through corners. With a Commando the next straight needs to begin as you enter the preceding corner. Get on the gas really early. A Seeley-framed bike often comes out of corners much faster than many others. It takes a lot of power on the straights to beat that.

acotrel said:

The hot exhaust valve was apparently the source of detonation when a Manx engine is used with very lean carburation. When I was a kid, some of my mates raced Manxes. An exhaust valve cost 15 pounds ans a piston cost 30 pounds. At that time I was earning about 20 pounds per week. I thought my mates were insane. I could not see the reason for sodiem-cooled exhaust valves. But in our days, most people raced using methanol, so detonation was not a problem. In the UK and America these days, most guys probably race Commandos using petrol, so the detonation problem is probably still there.
I always believed that If I lowered the needle in the carb until I got the miss, then raised it one notch, that was lean enough. However it is more subtle than that.
Cricket is a Pommie game. Tuning a Manx Norton to go fast using petrol is probably similar to that. - You would need the patience of Jobe.

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How does the sodium-cooled valve work?

concours said:

How does the sodium-cooled valve work?

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If a serious question, it liquefies at low temperature.
The problem is with time they can corrode the valve itself leading to the head parting company.

I know there is at least one other Ford FE (390/428/427) fan here, even Ford who used those valves recommended replacement at short intervals.

Time Warp said:

If a serious question, it liquefies at low temperature.
The problem is with time they can corrode the valve itself leading to the head parting company.

I know there is at least one other Ford FE (390/428/427) fan here, even Ford who used those valves recommended replacement at short intervals.

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Serious question.
Yes, I know the science involved, Dad splained it to me when I was 10-12 years old.
Which of the FE engines used the sodium filled valves?


I think @acotrel has some very fascinating experience/knowledge that needs to come out and enlighten us.

Is sarcasm lost on the Americans?