Atlas Barrel - rebore to +0.060, hone or ditch?

bill · Apr 9, 2017

as i stated the thinnest wall that LA sleeve lists is .0625 THAT IS considered a thin wall sleeve. as to curzon and white doing it that is there choice and NOT one i would do nor comnoz anymore from our chats as he has seen the same thing, it has worked on SOME but it is to risky. you KEEP going back to OTHER cylinders with no trouble and i agree it can and has been done on a lot of stuff BUT a norton 750 cylinder IMHO is NOT the prime candidate.

Rohan said:
[.
Thin walled sleeves are very common in the automotive world - well proven technology.

So why then are Anthony Curzon and Peter White of the NOC mentioning they have had more than a few engines (750 Norton engines) done with this ? And even recommending folks to do it.

Just because you have doubts doesn't mean it can't be done, successfully, by skilled operators.
LA Sleeve have sold gazillions of sleeves for all types of engines.
Search here and see how many folks mention them...

Hortons Norton · Apr 9, 2017

Hello Mike, If it were me I would see if there is someone close by that could take a close look at it. To me it looks like a cut down to the next size or two might do it. Some can tell just by looking at it, if they say no well then....... I'm not sure what the safest size to go down to is, I'm sure that also will bring out some more discussion. I can't tell by the photos just how bad it is. Chuck.

swooshdave · Apr 10, 2017

Are the original barrels of for the Nortons sleeved or was it cast all as one piece?

bill · Apr 10, 2017

it was a one piece casting than machined.

swooshdave said:
Are the original barrels of for the Nortons sleeved or was it cast all as one piece?

Mike T · Apr 10, 2017

Thank you all very much for your great feedback. I really appreciate it and it's given me a lot to think about. I'll let you know how I get on in the next couple of weeks.

Bernhard · Apr 11, 2017

by swooshdave » Mon Apr 10, 2017 7:05 pm
Are the original barrels of for the Nortons sleeved or was it cast all as one piece?

postby bill » Tue Apr 11, 2017 2:05 am
it was a one piece casting than machined.

No, no ,no :!:
The barrel quite clearly was cast iron, with a spun cast liner pressed into it- it is NOT one piece, the twin cylinder came as 3 yes THREE pieces :!:

The liner was bored out on a lathe, then pressed into the barrel the boredout to size then honed- anyone who disputes this is talking out of his/her socks :!: :shock:

swooshdave · Apr 11, 2017

Bernhard said:
by swooshdave » Mon Apr 10, 2017 7:05 pm
Are the original barrels of for the Nortons sleeved or was it cast all as one piece?

postby bill » Tue Apr 11, 2017 2:05 am
it was a one piece casting than machined.

No, no ,no :!:
The barrel quite clearly was cast iron, with a spun cast liner pressed into it- it is NOT one piece, the twin cylinder came as 3 yes THREE pieces :!:

The liner was bored out on a lathe, then pressed into the barrel the boredout to size then honed- anyone who disputes this is talking out of his/her socks :!: :shock:

I didn't know windy wore socks! :mrgreen:

lcrken · Apr 11, 2017

The Norton twin cylinder blocks have been a one-piece iron casting since the original design of the 500 cc Model 7 Dominator introduced in 1948. That has been the design for all the descendents of that engine, including 600 cc, 650 cc, 750 cc, and 850 cc variants. I don't know where you got the idea that they had liners, Bernhard, bit it's completely wrong. I have cut a number of them apart, as well as boring the 850s out for 920 kit sleeves, and they are definitely all one piece. You can find the same info in the Norton history books, like Roy Bacon et. al., but I'm basing my statements on personal examination.

Ken

Rohan · Apr 11, 2017

Yes, if the iron cylinders had been sleeved from new, we wouldn't need to be having this discussion.
Just press out the old sleeve, and in with the new.

Nortons did fit sleeves, into alloy cylinders (inter and manx - and 500T ?).
As did Wellworthy, who provided some cylinder (and heads) for some models.
But they were cast in, so getting them out isn't simple at all.

Bernhard · Apr 13, 2017

lcrken said:
The Norton twin cylinder blocks have been a one-piece iron casting since the original design of the 500 cc Model 7 Dominator introduced in 1948. That has been the design for all the descendents of that engine, including 600 cc, 650 cc, 750 cc, and 850 cc variants. I don't know where you got the idea that they had liners, Bernhard, bit it's completely wrong. I have cut a number of them apart, as well as boring the 850s out for 920 kit sleeves, and they are definitely all one piece. You can find the same info in the Norton history books, like Roy Bacon et. al., but I'm basing my statements on personal examination. Ken

Original question refers to ATLAS :!: :shock:
Atlas Barrel - rebore to +0.060, hone or ditch?

by Bernhard » Fri Apr 07, 2017 6:03 am
Bore looks too far gone with all that rust, the normal method would be to have the rusted sleeve pressed out and another pressed into the barrel –I have had this done in the past HTH

Since I have had this done in the past, when the liner broke at the top and dropped down in the barrel locking up the crankshaft, you are 100% wrong, as I was referring to the Atlas 750.
There are spun cast iron liners available for the 650, 750 (Both spigoted and non spigot)
You are not paying attention there :!:

lcrken · Apr 13, 2017

Bernhard,

If you had an Atlas barrel with liners that you could remove, it's because someone had previously bored it for liners. The Atlas barrels did not come from the factory with liners.

Ken

lcrken · Apr 13, 2017

Picture of an Atlas cylinder with broken section showing grain of cast iron. Very clearly no liners here. Also no liners visible in the original post pictures.

Atlas Barrel - rebore to +0.060, hone or ditch?

Ken

texasSlick · Apr 13, 2017

I happen to have my Atlas cylinders sitting on my credenza. As I am the original owner, I can attest to the fact these are as originally fitted.

Examination with a 5X loupe reveals:

1) There is a uniform sand casting texture where the outer diameters of the cylinders join the base between the tappet bores (the non machined area inside the gasket flange). There is a smaller non machined area at the rear, dead center between the cylinders, that has the same texture characteristics.

2) There is also a generous radius where the outer diameter of the cylinder joins the non machined base area.

3) There is no visible joint in the machined surface where the lower cylinder spigots merge into the tappet bores.

These factors rule out a pressed in liner. Let's put this issue aside and return to helping the OP with his original question.

Slick

lcrken · Apr 13, 2017

texasSlick said:
These factors rule out a pressed in liner. Let's put this issue aside and return to helping the OP with his original question.

Slick

Good idea. I've posted too much already, and none of it about his original question.

Ken

Rohan · Apr 14, 2017

But you've / we've clarified a number of things the OP may need to have been concerned about,
after some of the posts here !

Mike T · Apr 22, 2017

Thank you everyone. I'm still following this thread with great interest and I appreciate all your guidance.

I haven't visited the machine shop yet, but only yesterday I came across a possible alternative..

I may have the opportunity to purchase 1 or 2 barrels locally. One is a barrel by itself and in nice condition. It looks like it might be usable or may just require a hone. However, the second barrel and head are in beautiful condition.

The stamping numbers on the barrel are the same as the Atlas project, but it looks like they are for a Commando, not Atlas?

Neither barrel seems to be "spigoted", which I understand is where there is a lip on the head of the barrel bores that fit into the grooves of the Atlas cylinder valve cavities in the cylinder head. The second barrel/head looks like it has been newly re-bored or honed and is in very nice looking condition. I'm not sure if those valves look right, but I will get the chance to see it again soon. 2 of the valves look to have seats and the other 2 don't.

My question is, would these barrels and the head fit the Atlas crankcases or would there be a lot of other things I would need to consider?

Thanks again for all your help. I'm very grateful.

Here's a video containing a few clips and photos of the two barrels & head.
[video]https://www.youtube.com/watch?v=tYKM9uipTyw[/video]

Hortons Norton · Apr 22, 2017

I think the barrels would fit but the head would need some other way to attach the Atlas style head fixing bracket?? You may be able to drill the center hole and tap to size?? Nice looking stuff there. Also the head bolts may be different too.

Rohan · Apr 22, 2017

And also the Commando head has the head oiling fitting to the side, not on top.
So would stand out as different, and would require different oil line fittings.

Whether performance would be any different is a question, not seen any discussion of this ?
Probably not...

annajeannette · May 23, 2017

Mike T said:
Hello guys
May I ask for your advice concerning the barrel for my Atlas project bike? The engine was seized when I got the bike and I managed to remove the piston that was stuck. The barrel is in good condition but one of the bores is pretty rusty and I was thinking of getting it bored to the next size. But when I checked the pistons, they are already +0.040 over standard.
My question is, should I even attempt to go for a re-bore of +0.060 over standard or after looking at the cylinders do you think that it might only need a hone?
Thanks for your help

Hello I would get them sleeved at a good engineering workshop do not go over 40+ your Atlas will shake your teeth out, yourS Anna J

Here are a few pics of the barrel and I have more if needed:

Rohan · May 23, 2017

Would you like some lessons in how to add your text to a quote Anna,
your message seems to have been buried in the vast expanse of the original post....
You are allowed to trim some or all of the pics away too, no point in repeating what we've already seen.

And, is +0.040 really the threshold of Atlas's vibrating ??? !!!
You know this, for sure ?

Atlas Barrel - rebore to +0.060, hone or ditch?

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