Mysterious parts, 
not so visible failures, special tools, home made spares and other stuff

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During the years I have the WD16H, and while making this website and answering people on various items, I found that a number of parts are not given in the spare parts lists or described in the Maintenance & Instruction Manuals that I have. The consistency with which they are not given is puzzling. Nobody bothered to mention it, or Norton was not interested in correcting it.

Other parts are prone to failure but their failure is not always obvious. Additionally it is helpful to have some dimensions of parts not so readily available anymore like friction discs for front fork and steering damper.

The engineering of the bike is lovely crude. Any superfluous oil is just discarded on the road through multiple copper pipes. Length and routing of those pipes hardly ever are original nowadays. They tend to break off or have been cut short after kinking. If you have to make new ones, some guidance is given on how to get the original look again. When building up a bike from parts, some of them are difficult to find as they are not clearly visible in the illustrated parts list. Things like wheel axle distance bushes can be a problem to find.
I have made some drawings giving the dimensions of them as they can be easily reproduced.   

Also some special tool are given which can be made to ease tinkering on the bike.

I hope my experiences can be of help. I expect this to become a small list in the end. It is not always to be taken as advice. It is always your own decision and responsibility if you follow what I did/do. 


Crankcase breather valve.
To alleviate the pressure differences which develop in the crankcase when the piston is going up and down, a pressure relieve system is usually utilized. On the 16H and Big 4 engine, this consists of a  a pressure relieve valve using a steel ball to close the case when the piston goes up, and vents when the piston goes down. (There is another channel drilled in the crankcase LH side below the main axle, it will breathe also, but I am not sure what the exact function is). The crankcase breather tube is visible behind the top end of the primary chain case and pointed in the direction of the rear chain on which it spits any excess of oil. This copper breather tube, steel ball valve and the brass nipples are not very obvious in the spare parts list.  It is listed under Transmission as "Crankcase breather, complete with Pipe" part no. 9531.  It would be more appropriate in the Engine section!
The Maintenance and Instruction manuals do refer to a valve, without further description of the configuration.
I did not know a "ball" valve was supposed to be there until I opened an engine which I obtained later, on which it was mounted. Apparently I just didn't read the M&I manual properly before, but if I did I wouldn't know what it looked like!
I have found more engines without the valve installed. As a slight under pressure in de crankcase, when the piston goes up, is beneficial in sucking some oil through the cylinder backwall channel (lubricating the rear of the piston skirt). I think it should be present and working.

      Bottom view crankcase breather valve                                Top view crankcase breather valve

Felt and leather washers
 Many bikes have lost their felt and leather washers over the years. Many people don't even know there should be any at all. The M&I manual does sometimes mention them, but they are relatively mysterious.
I made them all and think they are useful in  keeping muck out and grease in. Between the primary chaincase and the engine crankcase a leather washer is used. Between the primary chaincase and the gearbox a felt washers is used. I added a felt washer between the magneto and the timing chain case. Felt washers were further used for : clutch nut, gear change pawl carrier, wheel hub bearings (both sides), inside primary chaincase between footrest tube and outer casing, and sheets of packing felt between the top frame tube and the petrol tank on "later" bikes. ("Early" bikes used rubber sheets (See pictures of most original WD16H).  

Gearbox main axle dished spring washer
The exploded view drawings of the gearbox in the Maintenance and Instrucion manual as well as various books, show a dished steel spring washer at the end of the main axle. I personally have never found such a washer in a gearbox, and wonder if they were actually used on all boxes, or only the later ones. Its not given in the spare parts list of either old or newer contracts or postwar civilian lists. The dimensions are I.D. 5/8", O.D. 1 7/16", steel thickness 1/64" and dished height 1/16" as measured from a used washer by Lex Schmidt.

Kickstarter axle cork oil retainer washer
To prevent the oil leaving the gearbox along the kickstarter axle there is a cork washer fitting in a recess in the gearbox cover.
The washer p/n 3810 is not shown on the M&I manual exploded views. People have replaced the cork with a proper size O ring.
If you do, make sure it is chemical resistant to the oil. Viton will definitely do the job.

Carburetter needle jet
The Needle jet in the 276 carburetter  has been described in the original AMAL specification sheets for WD16H and B4 as "standard". The Spare parts lists and the VAOS lists describe it just as Needle Jet with part number AM/4/061.
The Burlen Ltd company, (present official AMAL manufacturer, see links page) stated that the "standard" part was actually the 1065. These were not marked. For reason of optimisation, there are alternative needle jets available numbered, 105, 106, 107, 108 and 109. The number signifies the internal diameter in 1/1000th of an inch.

Fork Spindle Knurled Adjusting Washers
The drawing of the front fork as given in the Maintenance & Instruction manual is not completely correct. The drawing only shows 4 knurled washers (10) but it have to be 6 as stated by the spare parts lists and logic. I adapted the drawing to show the two additional washers (10) on the bottom rear spindle.

   Click picture to enlarge


Magdyno platform variations
 When restoring a military 16 H or Big 4 from scratch, one unfortunate finding could be that the timing chain as dictated by the Magdyno sprocket does not run in line with the driving timing sprocket.
 When using the wrong platform, there is no gap between the rear of the timing chain cover and the Magdyno. When using the correct platform there should be a clear gap between those parts. I cannot give an exact measurement for the gap as there are many variations but some measured results are around 3/16" (4,7) mm.  To prevent muck to enter the timing chest through this gap I have made a fitting felt washer mount between the Magdyno and the timing chain with such dimension that it does not interfere with the rotating Magdyno shaft and is not to obtrusive when looking at it from the outside.
 The in-line deviation will not happen (on military bikes) when using the cast iron version as made during the war (casting number 12311), but it can happen when applying the aluminium version as used before and after the war. The correct aluminium version has a casting number 11699 on it. One incorrect aluminium version has a casting number 13814 on it, there may be more aluminium casting numbers.
 The civilian Norton part number changed from 3711 (pre war military and civilian prior to 1938) to 3711A for the cast iron version to A2/117 in 1946 and 1947.
 The 1938/39 civilian Norton part number was 8918, but its not clear yet if they deviated in dimensions or casting number and whether they are identical to the pre war 1938/1938 civilian version.
 There has also been a part number C2/117 but its not known (at this moment of writing) in what sense it differs from A2/117 or 3711(A). The number 13814 was found on a platform labelled C2/117.



Main Gear Wheel Sleeve Bearing Roller Retainer Washer.
Pictures of the "exploded view" gearbox show that the rollers in the main gear wheel are neatly housed. What it does not show is that the rollers are closed into the main gear wheel by a steel washer, against which the bronze clutch thrust washer rotates when activating the clutch. Look at the picture given in the gearbox and transmission page where I added the washer for clarity.
This hardened steel washer has the tendency to fracture. Two of the 3 gearboxes I have showed this to be the case. The washer is given in the spare parts lists (all) under no 3598 (Main Gear Wheel Sleeve Bearing Roller Retainer Washer).  I have however not been able to find original replacements for them, and had them made from a cold work tool steel (AISI D2 or UNS T30402) and hardened to 59 Rc. Remains of the original were measured to be 60 Rc so I think I am close enough.

 Click to enlarge    Click picture to enlarge

Loosening clutch nuts
On some bikes, you see an additional disc in the large depression produced in the primary chain case to house the clutch. This is usually the result of adjustment of the clutch disengagement while actually the clutch nut has come loose.
So if you ever have the urge to adjust the clutch disengagement stroke, first check the central nut on the clutch. Despite the spring washer behind it, it loosens on occasion.


OIL AND GREASE STUFF (See alo the running a 16H or Big 4 page)

Oil return lines.
Anybody not having used his bike for some time will have experienced the blubbering noises and heavy kickstarter actuation when trying to start his machine.  I know, everybody has a perfect oil pump, but me?
The oil tank has drained itself into the engine crankcase after finding its way past the gears of the oil pump.
My solution to the problem is adding a tap into the oil feed line. Dangerous? only when you forget to open it before starting.  If you don't trust yourself, hang a "remove before flight" banner on your handlebar! Modern motorcycles do it for their disk brake lock. 
I have used it for 20 years now and forgot it twice. Because I regularly check the oil tell tale after start up, the omission shows itself immediately. With such a "high" powered engine as the 16H, I really don't expect a lot of additional wear on the internals. I have the experience that you can ride more than 20 km without oil flowing for some time if you don't revv it up too much. OK I know it is not meant to be so! but the damage seems to have been negligible as I have used it for years afterwards without noticeable problems.

Valve grease nipples.
One of the most amazing features on the 16H engine are its valves. There are grease nipples on the valve guides as a token addition to subdue valve stem wear. Initially I used to give them a squirt of high temp molybdenum based grease. This usually resulted in a fairly sizable smoke curtain at the beginning of a trip.
I stopped greasing them as I don't think it has any use. I am now about 15.000 miles further since I stoppped greasing and it still works. I know I don't have the maximum compression, and I don't go faster than 50 MPH anyhow because that is a very uncomfortable speed on a dinosaur suspension. But what the heck, put in a new set of valves and guides and I will ride into my old age pension!
These bikes are rugged!!!!    I love it!

Latest tip I got was the use of : "(air) gun grease". This apparently has a very high temperature resistance, and would therefore be able to withstand the temperatures of the cylinder head. I will try to get some and have a go at it myself. Keep you posted. I will first try to do some temperature measurements on the barrel using a non contact gauge as used by modellers. Then see if it is useful.

Oil regulating grub screw on top of timing cover
An often asked question reaching me is about the setting of the grub screw valve on top of the timing cover.
The setting of this grub screw regulates the amount of oil being fed to the rear of the piston/cylinder.
It is not properly described in the military Maintenance and Instruction manuals people usually use as guide.
The setting of this was done at the factory and should normally not need to be touched. After 60 odd years however some cleaning of the insides may be required or the workmanship of previous owners needs to be checked.
The standard setting of this screw is one turn from the fully closed position. (According to WC Haycraft in 1936 and EM Franks in 1952).
 Its difficult to say if this is still correct for all engines, but depending on the state of the engine it may need some adjustment.
It should be adjusted such that there is a minimal amount of smoke coming from the exhaust. As the smoke from the exhaust does not only come from this setting, its a setting with lots of possible positions.
The standard setting is therefore the most likely correct one.

Oil drain pipes all over the motorcycle
The M/C has a number of pipes added to direct oil coming from various positions to be discarded at the underside of the M/C in an probably vain attempt to keep the Gentlemen's trousers clean.
They are: "Tappet guide oil pipe", "Magneto chain cover oil pipe", "Crankcase breather pipe" and not on engine but oil tank the "Oil tank air release pipe"
The routing and lengths of these pipes are usually not as original anymore after 70 years of tinkering by professionals and hobbyists alike.
Based on contemporary pictures I come to the following routing (dotted lines). Lengths to suit. Both Tappet guide oil pipe and Magneto chain cover oil pipe were routed between the oil feed and return lines and the crankcase and ended approximately below the footrest.

    Click picture to enlarge, note:  lines on my bike as shown are not "correct".



Attached list (MS Excel file) shows all nuts and bolt sizes on the Norton 16H. Most of these are also used on the Big 4.
The list can be useful if you are searching what taps and dies you might need to clean up threads or recreate fasteners.



Handy to know when searching for new friction discs, or to make them yourself.

  Click picture to enlarge

Front and rear axle distance bushes

  Click picture to enlarge


Norton Clutch puller
  Click picture to enlarge

Wheel bearing nut spanner
 Click picture to enlarge