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Sleeving Atlas & 650 cylinders.

Norton Models (not Commando or P11)

Re: Sleeving Atlas & 650 cylinders.

Postby texasSlick » Sat Feb 04, 2017 8:45 am

I am following this thread with interest.

My experience with liners has been limited to one case of a liquid cooled engine, and as Triton and bill write, they are an entirely different kettle of fish.

As an engineer, I see the problem of liner replacement in air cooled engines being that of heat transfer. One must achieve virtually a molecular bond between the liner and barrel, in order to achieve original heat transfer characteristics. Even fine honing is not good enough, and neither will a shrink fit eliminate the micro gap between components.

I have heard of copper plating the bore as way of getting the molecular bond, but I cannot speak from any experience. I am skeptical that press fitting the liner past copper will do anything except scrape the copper away. Perhaps shrink fitting a dry ice chilled liner into a copper plated bore will "flow" the copper into microscopic pores, and do the trick.

The degree of interference fit must also be controlled. Too tight, and undue stresses will be set up in the barrels, and too little will not extrude the copper.

Surely, successful resleeving is an art.

Slick
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Re: Sleeving Atlas & 650 cylinders.

Postby Triton Thrasher » Sat Feb 04, 2017 11:03 am

Liners do work. I've ridden a sleeved AJS 500 single and it worked just fine.

But there has to be enough metal left after the cylinder is bored out for the sleeve. Enough to avoid worse than usual distortion and enough so the barrel doesn't snap off above the bottom flange.
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Re: Sleeving Atlas & 650 cylinders.

Postby Rohan » Sat Feb 04, 2017 1:47 pm

texasSlick wrote:As an engineer, I see the problem of liner replacement in air cooled engines being that of heat transfer. One must achieve virtually a molecular bond between the liner and barrel, in order to achieve original heat transfer characteristics. Even fine honing is not good enough, and neither will a shrink fit eliminate the micro gap between components.
Slick


Actually, this is not strictly true.
And, why would water cooling make the sleeve contact requirement any different anyway ?
Apart from that many diesels were aircooled from some makers...

Since sleeving sidevalve engines since WW2 was a VERY common practice - eeking out more miles on a shoestring budget - it is suggested in the motorcycle press that as the engine gets hotter, the sleeve can ONLY expand outwards - so the already tight fit of the sleeve gets better, heat conductivity wise.
Heat will always flow from hotter to colder, so even if the contact was only minimal, all those minimal points will flow heat - or the bloomin thing would melt !
It takes considerable muscle to press the sleeves in too, so the contact won't be too minimal !

As I said, I have an ex-WD M20 engine that has been sleeved, and done extensive miles since then.
And Mr Curzon sez he's had a number of Nortons sleeved, successfully.

Now, it is also mentioned that the early 650 and Atlas engines had rather minimal metal in the cylinder walls.
Isn't there a memo noting that the wall thickness was increased, quite early in the oroduction of these ?

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Re: Sleeving Atlas & 650 cylinders.

Postby texasSlick » Sat Feb 04, 2017 2:46 pm

Rohan wrote and my comments:

".... why would water cooling make the sleeve contact requirement any different anyway ?"

Because the cooling medium ( water) contacts the liner directly. It becomes irrelevant if the contact of sleeve and block is imperfect.

" it is suggested in the motorcycle press that as the engine gets hotter, the sleeve can ONLY expand outwards - so the already tight fit of the sleeve gets better, heat conductivity wise. The fit gets tighter, but the heat conductivity likely does not improve much.
Heat will always flow from hotter to colder, true so even if the contact was only minimal, all those minimal points will flow heat at a significantly reduced rate as compared to a perfect molecular bond- or the bloomin thing would melt !" From what I read in the posts above, that seems to be the problem!

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Re: Sleeving Atlas & 650 cylinders.

Postby Triton Thrasher » Sat Feb 04, 2017 3:09 pm

In service, heat conduction from the liner to the casting isn't an acute problem.
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Re: Sleeving Atlas & 650 cylinders.

Postby texasSlick » Sat Feb 04, 2017 4:01 pm

Triton Thrasher wrote:In service, heat conduction from the liner to the casting isn't an acute problem.


Several of the posts above describe seize ups as the failure resulting from a relining job. If so, that is a heat conduction problem.

Other failures noted above stem from taking too much metal away. That is an inexcusable error on the machinists part, unless the cylinder design simply was inadequate in sufficient metal in the first place. I will forgive the machinist if the customer insisted on an over bore liner to gain more displacement.

As I stated above, I have no experience in sleeve jobs .... i am not saying they cannot be successful .... however, I am more expert in heat transfer than the average engineer, and IMO the contact of the liner to casting will be a major determining factor in the success or failure of an air cooled cylinder reline job. I merely wished to point this out so those who contemplate sleeving barrels will favor a shop that uses a process that addresses this point.

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Re: Sleeving Atlas & 650 cylinders.

Postby Rohan » Sat Feb 04, 2017 4:53 pm

Seize ups would have to be related to the clearance they were bored to ?

The M20 engine I have with good miles on it just seemed to have a normal piston clearance to the bore,
(and sidevalve engines traditionally run pretty hot) so inadequate clearance could well be the culprit you mention.

As said before too, watercooled engines really wouldn't make any difference to good contact to the sleeve.
Plenty of diesel engines use this system - no oversize pistons, just a new sleeve supplied with new std piston.
They are just pressed in dry, with a suitable interference fit, and then honed to suitable clearance.
Very common practice in the diesel world.

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Re: Sleeving Atlas & 650 cylinders.

Postby bill » Sat Feb 04, 2017 5:01 pm

it is not a heat issue. it is failure of the casting above the base flange.

texasSlick wrote:Rohan wrote and my comments:

[/color]- or the bloomin thing would melt !" From what I read in the posts above, that seems to be the problem!

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Re: Sleeving Atlas & 650 cylinders.

Postby Triton Thrasher » Sun Feb 05, 2017 2:00 am

texasSlick wrote:Several of the posts above describe seize ups as the failure resulting from a relining job. If so, that is a heat conduction problem.


You're jumping to a dubious conclusion, perhaps because you "are more expert in heat transfer" and are displaying that knowledge at every opportunity.


A siezure after re-sleeving is highly likely to have the same cause as the very common siezures after ordinary rebores: the stupid machinist has got the piston too bloody tight in the bore! Or- the stupid owner is labouring it up hills at low rpm.
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Re: Sleeving Atlas & 650 cylinders.

Postby bill » Sun Feb 05, 2017 6:05 am

the seizure was NOT from a sleeve job . I had made an attempt to fit a set of 810 pistons in a 750 cylinder. the results was it was to thin.

texasSlick wrote:Several of the posts above describe seize ups as the failure resulting from a relining job. If so, that is a heat conduction problem.
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Re: Sleeving Atlas & 650 cylinders.

Postby norton bob » Sun Feb 05, 2017 6:56 am

Some engines have substantial metal and the liner makes little change to the sructural strength. Norton twins particularly the 99 and 650 and Atlas have a history of fracturing around the base,especially when tuned/raced. I have seen several linered 99 barrels where the liner can be seen through the fins. Liners have also been known to drop and break off lumps. When there is no option then a liner is an answer, I have some hopes that new 88/99/650 barrells will be availiable in the future from a uk manufacturer, When you think about it the last ones were produced in the early 1960's no wonder they are scarce.

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Re: Sleeving Atlas & 650 cylinders.

Postby Rohan » Sun Feb 05, 2017 10:07 pm

norton bob wrote: Norton twins particularly the 99 and 650 and Atlas have a history of fracturing around the base,especially when tuned/raced.


Again, isn't this related to that the early 650 and Atlas cylinders (and the earlier 99 design) were a bit thin on metal around bores.

At some point not too far into their life, the (650 and Atlas) cylinders were strengthened in this area ?
(The 99 never was, its production life ending circa 1962).

I'm sure this has been discussed here before, possibly by BenG ?

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Re: Sleeving Atlas & 650 cylinders.

Postby bad_friday » Mon Feb 06, 2017 2:19 am

norton bob wrote:…I have some hopes that new 88/99/650 barrells will be availiable in the future from a uk manufacturer…

On 31th. January 17 I was told by Joe Seiffert it will take at least six months till the new barrels will be available at Andover Norton.

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Re: Sleeving Atlas & 650 cylinders.

Postby norton bob » Mon Feb 06, 2017 4:04 am

Difrerent source of supply for cylinders. In the uk most of non Commando Nortons in use and without a supply of cylinders are 7,77, 88,99 ,650. And there are lots of these. 750 cylinders don't seem to be a problem .

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Re: Sleeving Atlas & 650 cylinders.

Postby Bernhard » Mon Feb 06, 2017 4:57 am

norton bob wrote:Difrerent source of supply for cylinders. In the uk most of non Commando Nortons in use and without a supply of cylinders are 7,77, 88,99 ,650. And there are lots of these. 750 cylinders don't seem to be a problem .



There may be a shortage of except for the 750s, but in the early life of the Commando and during the Atlas production run used 750 cylinders were like hen’s teeth :!:

There also may be a shortage of liners, but it is relativity easy to get some liners turned up on a lathe, and they can be left slightly oversize to fit the barrel -no problem.

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