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Atlas high pressure head feed pipe


Thinking it would be good insurance to replace the plastic pipe (which I recently repaired) ,I was a bit dismayed by the price.  Has anyone found a more reasonable DIY  route?.


Good Morning Robert - Are you replacing the plastic pipe with a chrome or stainless steel Goodridge type aircraft spec hose ?  If so make sure that you specify the correct size banjo nuts.  Lots of people supply the metric banjo equivalent to the 3/8 inch banjo. Presumably because that is what people employ on their hydraulic brake hoses.  You need a 5/16 inch equivalent which is much less in demand and costs the earth...... Cheers, Howard   


Hi Howard, I was thinking more on the lines of replacing the plastic line only and heating/cold shrinking the unions (as I have already done with the old line) . Worked fine (probably the same method as the orriginal manufacture) ,but the line must be aged and probably a bit brittle. Could do it in copper or even go back to a low pressure system  with scrolled spindles .The current plain spindles with no flats and only a hole  have wear and will probably need replacing anyway.I have managed to get the low pressure system working better on the 99 with a few mods.


Yes the original fit on my 1966 650 was in plated copper with soldered banjo unions.  Then I once replaced  one on my Atlas in the seventies and the Norton part that arrived from Joe Francis was a nylon pipe with the banjos presumably pushed in with heat applied to the piping.  I can't remember what my 69 Commando had but I don't think it was in copper. Good luck, howard


Never-ever heat the black nylon lines to install. 

Mount/clamp the line, slightly extended,  in a normal flaring tool.

Clamp flaring tool in a vice.

With a plastic mallet, pound in the fitting in the cold line.

A simple twist test will show how tight it really is, which will be MUCH  tighter than a heated line would be.     Heating the line ruins it!!!

Been doing it this was for commando and the featherbed for decades.

The fittings are valuable but the black nylon lines are very inexpensive to renew. I buy 10' at a time for a few $

Hi Robert

My understanding is that the proddy racing bikes of the early 60's ,preped by Syd Lawton, were blue-printed, but virtually standard. So Low pressure rocker feed, original "weaker" con-rods (no oil holes either), 3-start worm gear set on earlier oil pump.

They went very well and reliably!!

On my own 650SS am trying the low pressure rocker feed, later con-rods (blanked holes), later oil pump and thinking of going back to 3-start worm gear set (now I know who stocks it). At moment doing some oil pressure tests with various oils.

My Low pressure rocker feed (discarded the soldered Y pipe) is 3/16" rubber pipe from return to oil tank (with adaptor mod') , tee piece and metal banjos.

If you would like the part nos

I'll sort them out for you.



Hi Tim,  From my experiments with the low pressure feed ,I suspect that  with an engine used  mostly at the higher rev range oil supply was  enough. But pottering about at low revs and short journeys (commuting) found the system lacking. The Jubillee tank fitting recommended in the old days provided me with far too much  oil , so a brass plug threaded in and slowly increased in bore size to somewhere between the jubillee and std Norton  size  got me to where I needed to be. I suspect that if the bike was to be used for motorway cruising (it won't !), then the oil supply would become too much and start to cause smoke from the unsealed inlets. On the Commando any excess oil can flow easily to the cams and be usefull , On the Dommy an additional (external?) drain near the inlets would perhaps allow a higher flow system ,perhaps just the later bigger pump with the 3 start gear set. 


I'm in the USA, so you will need to find a Brit source. Lots of american companies can't legally export without special permits and it is criminal to have some one who bypass the law.

However this is like what I use. $1 a foot. On a cold start (72 combat) I once showed 150psi on my gauge. The pressure rating is quite temperature sensitive So less than intelligent routing can cause problems. All my nortons use this except where a metal hard line is used  for "show".

nylon 11

The .170" ID is a light press fit to get the barb started for the mallet hit.

I use the same stuff in 1/8" OD for running to the pressure gauge .

Hi Robert

That's interesting and only time I've heard of a smokey engine on the low pressure rocker feed.

Since purchasing a workshop oil gauge it's been an education. Am adjusting the PRV [Pressure Relief Valve] with shims. The concept of buying a PRV "already set-up" seems crackers now, having seen my first readings off the clock and had to hastily kill the engine.

Caveat to blocking oil holes in con-rods is that you have to allow more miles for running in; pistons may pick-up if too aggressive with the throttle early in the running-in period.

What started me off down this route were previous discussions and articles in archived Roadholder issues on High pressure rocker feed, plain rocker shafts, open holes in con-rods to get rid of excess oil pressure. Then to cap it all the comment to the effect the high output oil pump solved a problem which wasn't there in the first place.

Like you I'm unlikely to be on a motorway; my favoured route is over the Yorkshire Wolds with, perhaps a stop at Fridaythorpe cafe and a natter. Or not and do the 50 miles without a stop.

Let us know how your repairs go.





Hi Tim, I only got the smoke and oily plugs with the Jubilee tank fitting ,once flow reduced all is well.I am interested in your findings re oil pressure as I am currently running a fully sinth 10/40 ,probably a bit of a gamble. Looks like a member has found me a new feed pipe set  , this is the best club !.


My Atlas engined 99 has a plastic rocker oil line form Norvil. I was rather wary of it but it has seen many years and thousands of miles of use. The Atlas engine set up is bog standard. It's fine for normal running and revels in motorway work. No significant oil consumption noted so perhaps Norton got it pretty much right. 


 Our Atlas has also been reliable , any issues stem from a lack of oil changes ( wore the rings out big time) , wrong parts fitted, and poor quality pattern parts that bear the trusted names but are now rubbish.  


Hi Robert and fellow "nockers"

Am waiting now for some better weather to start the bike outside [without today's icy wind].

I also want to explore some ideas for improving the breathing, but after the oil types / pressures


Tried "Carlube Classic 20W50" from a local motor factor and am just amazed by it, firstly on the road;

smoother, more responsive engine then the oil pressure test.

Will write it up when I've put the monograde back in and adjusted the PRV to suit.


Hi Tim,  I have played with the breathing on the 99 DL  , trying to eliminate oil loss.  and mess!. Current set up is a 3/8" pipe up to the drilled  extended  tank neck (DL)  and connected with copper gas soldered end feed fittings ( idea as late 650/Atlas) and a 3/8"  breather pipe (from which only moist air comes.Oil loss eliminated,but  condensation forms in the tank (which never seems to get properly hot anyway,too much bimbling around!).Another reason for modern oil with additives.Tank has its winter warmer jacket on( Not seen under DL panels). Not an ideal set up ,better with an air/oil seperator to send fumes away from tank and a reed valve to reduce engine internal pressure and oil leaks. .Will be next project after getting Scottoiler and forks fine tuned.And heated grips re-fitted.-- washing machine and oven replaced,microwave stripped--------,et al.---------.


Hi Robert

Am not familiar with what goes on under the side panels of the Deluxe range. Perhaps you are describing the Froth Tower on top of the later 650 and 750 Atlas.

Have found my 650 produces far too much waste, even though it has a breather valve fitted just before the froth tower and the oil filler cap vent is blocked as per John Hudson advice.

Am pursuing the oil types comparison when we have a break in the awful weather, then some mods to the routing of breather recommended to me. Then I'll write it up.

While on subject of breathing: there were several versions of the rotating breather pictured somewhere in the archives.The Norton agents have settled on one as far as I can see.

Has anyone drilled out the Fixed breather (pre Atlas). If so what is the correct way to fit a new fixed breather to the drive side crankcase; do you line the holes with, say, the top gasket face, parallel to it? A clumsy question but just curious as can't find any guidance.


The early 650 had a timed breather like the 99 before it that just discharged to ground, later bikes have a froth tower with timed breather going to it. The DL has an extended under seat filler tube that I have converted to be a froth tower to mimic the 650/Atlas settup. Dont think there was ever a Dommy fixed breather. The timing of the breather was modified.Overbreathing is a sign of poor ring function and wetsumping.The breathing is a bit poor though and could stand some work.


Stationary Breather Plate = T2078 in L hand crankcase

Rotary Breather Plate on end of camshaft = T2075


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