Useless assorted Norton musings.....

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hobot said:
As all the solid mounted vertical twin use BF rather higher than 50% I hold that Norton picked the BF that used the least costly metal in cranks yet could still be isolated by the amount of rubber area supporting the mass.
Care to explain this? Are you suggesting Norton changed the balance factor when transitioning to the Commandos to save material costs?

You know we are only talking about maybe a few ounces of cast iron flywheel material. Any cost offset as a result of reducing the flywheel bob weight mass would certainly be more than off set by the energy and other costs of making that adjustment (machining, grinding and/or drilling).
 
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Well I was done with this thread then my friend Tony returned my Norton Dominator Master Parts list, 63- 68. It is split into two separate sections, 63-65 and 66-68. The left and right pistons listed for the 63-65 Atlas are #24246 and #24247.

The 66 to 68 Atlas has a different piston, left and right for it are the 25389 and 25390.
I confirmed with Les Emery of Norvil that these latter pistons are flat top, 8.9- 9 to one compression and that the later Atlas bikes had them from factory.The earlier pistons are the dished 7.5 to 7.6.
Authors Mick Walker and Steve Wilson are correct in their statements that the later Atlas had higher compression.

The later pistons are those that are famous for losing the heads. As to why someone might find a later Atlas on standard bore fitted with the dished pistons, Les suggested the pistons may have been changed out by owners or dealers looking to reduce the vibes of the high comp setup. A change from high back to low could also have been year or two down the road to avoid the piston top problem, which was becoming quite well known.

He also told me that much of the problem with vibration in the Atlas came from the balance factor. It was done piece work by a Brit who did not care about his work. This fellow would drill a few token holes in the flywheels then send them back to Nortons with a bill for balancing. Les has found Atlas cranks ranging anywhere fro 40% balance all the way to 92%, all done by the same very low cost subcontractor!
He said the correct number is 84% which is what he uses for all new Atlas builds. At this number he tells me they are quite smooth even at 9 to one.

I don't know what Bengs ad is other than there is no featherbed Atlas shown on the part that is visible, but there is a Commando S , which is a model that first appeared in 1969.



















 
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While we're talking about vibration; when I first put my Triton on the road, I really did lose fillings from my teeth.
 
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It occurred to me that the fellow driiling all those inexpensive but haphazard holes in the Norton flywheels might have secretly been on the Triumph payroll. :D

Triumph had the vibes too, didnt they?

Glen
 
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It occurred to me that WornTorn put up three pages of a Norton parts book with no compression ratio specifications printed in them. Les Emery's opinion is just that, an opinion, not a factory document, which again you have failed to come up with to support your Opinion.

Maybe you simply do not understand the difference between opinion and actual documentation?

Norton piston part#s 25389 & 25390 are for 7.5:1 pistons, and you will not find any real documentation otherwise because there is none.

Anyone can find opinions saying anything at all, and we are simply not interested in them, get it?
 
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Right, and your idea of documentation is an ad that you say is for the 1968 model year, except it for some reason it lists a 1969 Commando S? And no featherbed Atlas, which is the ONLY bike Mick Walker discusses in the aforementioned chapter and the model I was referring to?

He deals with the N15 and Ranger models in another part of the book.

Of course there was no Featherbed Atlas by 69, thats why it is missing, but never mind, that is DOCUMENTATION!


Forgive me if I go with the word of Les Emery, owner of Norvil, over the rabid babble of an internet troll named Beng.

Les Emery, Steve Wilson(author Norton Motorcycles), Mick Walker,(author Norton Dominators) are they all imagining things or is this compression ratio change some sort of conspiracy attempt?

On the later pistons, Les says he knows of one source who has buckets of them, n.o.s. but they are worthless due to the piston top problem.
 
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It is not an "ad" but a 24" x 18" service poster, the sort a dealer would have hanging in his shop. Maybe it is from 1969, but it does list Atlas scrambler and road bikes. And if you can not see the entire thing, with the road Atlas in the right column, your computer display must be set to a low resolution, if you know what that means.

Berliner sold up to 80% of Norton production during various years in the 1960s, including about 7000 Norton Atlas scramblers. Odd that they would not know what compression ratio they were, especially since they were the ones that pressured AMC for most of the changes that occurred in the bikes, and even the introduction of new models.

I have a 67' Atlas engine in my basement, just one of many I have seen first hand with STD. dished pistons in it. But according to you they all have dished pistons because every one just happens to have been swapped out by someone wanting lower compression and less performance, okay...... I will admit I never had any scrambler's in my hands, only road bikes, never liked the scramblers.

I love Norton history, and opinions are not history. I would love to see a factory paper showing which engine number they started putting high compression in Atlas engines, if it happened then it exists.

I have supplements that tell which engine number they started putting improved connecting rods and other changes in the Norton twin, but I do not have them all, including any that might have something about an Atlas compression change.

I have talked to some old dealers that thought the Atlas bikes had flat-tops, some that says they had dished pistons and some that did not remember a thing about it, that is why opinion is no good when you are interested in facts and actual history.

So WornTorn that is why I am going to stick with Berliner's document and the other factory documentation I have on the early Atlas, until something else show's up, which I will gladly accept when it does, showing Berliner maybe put the wrong data on their service poster.

I care too much for facts and history to simply accept opinions and hearsay, which I think is the smart and conservative way to go to uncover the truth, not "rabid rabble" as you put it in yet one more of your ego-driven name-calling sprees..



P.S. Here is a link to download a pdf copy of the 1968 Norton maintenance manual, which lists 7.5:1 compression for the Atlas and Atlas scrambler models, something I would call documentation...:

http://www.eurooldtimers.com/eng/manual ... -1968.html
 
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Triton Thrasher said:
While we're talking about vibration; when I first put my Triton on the road, I really did lose fillings from my teeth.
You are not the only one; this is the reason why I gave up large capacity parallel twins. They simply just shake themselves to bits; don’t ask me how I know.
 
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Bernhard said:
You are not the only one; this is the reason why I gave up large capacity parallel twins. They simply just shake themselves to bits; don’t ask me how I know.
Yes, I found when I had a test drive of a large parallel twin (steam engine, as in railway loco) that if someone opened the throttle too hard (sticky lever) at low revs, the vibration not only was intense, you could actually feel the chassis flex. Don't ask me how I know....

Apparently, if you open the throttle REALLY hard, you can pull the front wheels off the rails.
 
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