To help the novice on riding an old 16H or Big4 motorcycle.  I give my personal way of doing it with some additions by others.
Its not giving the ultimate procedures, just the way I do it, and its up to anybody to see what he does with it.


USE OF PETROL:

For petrol, I use unleaded 95 Octane (RON) fuel ("Euro 95", but may be named differently depending on the country you live in) since introduced in Holland several years ago. I have never added any lead supplement or other additions to the fuel.
These bikes were designed in the mid 1930 ties, in a time when leaded high octane fuel was only used for high performance aeroplane engines, and definitly not for down to earth sidevalve motorcycles.

Between 1939 and 1949 the only available petrol was "Pool Petrol".
"Pool Petrol meant that the physical assets, working capital and manpower of all petrol companies in the United Kingdom were pooled, each company receiving remuneration and depreciation on the assets contributed at agreed rates; prices, quantities and qualities of petroleum products came under Government control and competitive marketing between suppliers ceased; products were supplied by the members of the Board as far as possible in proportion to their pre-war deliveries, all (except lubricants) were sold under a Pool description, the selling price of each Pool product being subject to Government control.
The controlled prices were as far as possible fixed with a view to covering the costs of the Board without providing any profit.

Lubricating oil was the subject of separate pooling arrangements. The Lubricating Oils Pool was formed of 21 importers of base oils (including petrol companies), from whom it took over stocks, vehicles and storage facilities. Lubricants continued to be sold under brand names throughout the war. The Pool acted as sole wholesale seller of lubricants, supplying over 500 distributors and providing base oils of 30 different qualities."

(Info from CHAPTER 2. HISTORICAL DEVELOPMENT OF THE RETAIL MARKET FOR PETROL IN THE UNITED KINGDOM,  report ?? from the British "Competition Commision" website).

Octane ratings for pool petrol ranged between 67 and 80 percent, indicating that the present day petrol is far more explosion resistant than in those years. I am rather convinced you can have the bikes running on petroleum or white spirit.

The additon of lead was introduced to increase the "explosion resistance" and prevent "early combustion" of petrol, required for high compression engines. Increasing pressure leads to a higher tendency of the mixture to explode instead of burn or combust before top dead centre of the engine is reached. Neither of these tendencies is good for any engine.
It leads to overheating and loss of power.
Added advantage is that lead will work as a lubricant on e.g. valve seats.
With the relative low milage made with these machines nowadays (I do about 1000 km per year) I feel the additional wear on the valve (if so) to be acceptable.
 

USE OF OIL:

For engine oil, the original publications give straight SAE50 monograde oil. Its harder to get nowadays, but local oil suppliers still have it, and at a reasonable price. Don't go to the specialised motorcycle shop. They make millions on it. Companies delivering oil to for instance the inland shipping companies usually have it at a much better price. (e.g. Metropa Rotterdam, see links page).
If you cannot find Straight SAE50 oils, you can use 20W/50 multigrade oil, but if you have run on monograde before then you will first have to clean out the engine and oil system properly. Single grade oils are not so good in "catching" polutions in the oil. Using a multigrade oil after monograde oil may lead to the loosening of old sludge/dirt from the system. It might then block oilways.
I have used multigrade for about 10 years before I found a new monograde supplier. Because of it general lower viscosity, 20W/50 seems to leak a bit more!

For the gearbox, the documentation also gives the straight SAE 50 type oil. Here I have made an exception. I use SAE 80 hypoid oil in my gearbox. Not really thicker, but much better lubrication quality and especially developed for gearboxes. I just think it is better. I have spoken to other old bike riders and sometimes they actually add grease to the oil as well. If you have a leaky gearbox, that might help to reduce the bikes tendency "to mark its spot".

In General,  my motto is, "if it does not leak, thán you have to worry"!! (Not for my BMW though!)

STARTING

Starting the beast can be gruelsome, or a piece of cake. Below two procedures found in Norton riders handbooks.

The official way described in the riders manual of 1940 is as follows:
"With the petrol turned on and the carburetter slightly flooded, depress the kick-starter until the engine is on the compression stroke, that is, until it is impossible readily to depress the starter any further. Now raise the exhaust valve lifter and depress the kick-statrter a further two or three inches. Release the exhaust valve lifter and allow the kick-starter to return to its normal position. A long swinging kick on the starter should now start the engine, provided that the throttle is correctly set."

Missing in the description is the setting of air valve, ignition and throttle.

A later description found in a post 1942 riders handbook states the following procedure:
"Close air lever, set ignition two-thirds advanced position.
     Note: - with cold engine only, depress the plunger on top of the carburetter float chamber until it is apparent (by feel) that the chamber is full
                  of petrol. Do not allow the petrol to flood until it is oozes out of the carburetter. Free engine by depressing the kick-starter several
                  times with the exhaust lifter control raised.
Set throttle slightly open.
Depress the kick-starter as far as possible WITHOUT using the exhaust lifter control.
Raise the exhaust lifter control.
Depress the kick-starter a further inch.
Release the exhaust lifter control and allow the kick-starter to return to its normal position.
Give the kick-starter a long swinging kick, WITHOUT using the exhaust lifter control.
The engine should then fire.
If the engine back-fires, further retard the iginition, close the throttle a little, ands try again.
Do not rest the foot on the kick-starter cranck while the engine is running."

 
The slightly alternative way I use is that I doo lift the exhaust valve at the beginning of the long swinging kick in the assumption that it will result in a slightly faster rotation of the flywheel and thus aids the starting process. Be sure not to keep air valve open too long of course. Then you won't have sufficient fuel inhaled or have enough compression!

A trick aired on the BSA M20 Forum goes as follows: "When cold, tickle the carb, open the throttle fully for a couple of seconds for the petrol fumes to enter the inlet, close the throttle and proceed as usual".

In the end I have found every bike to be different, and you will have to fiddle around a bit to find the best way for your bike.
 

IGNITION TROUBLES

The above given procedures assume that your ingition coil in the Magneto is working properly and that there is no "leak"anywhere in your electrical system diverging the sparks to the wrong place.
These magneto's were never made to last 60 + years, and the materials used then do have their limits with respect to life.
Especially the Shellack, the dark orange/brown lacquer visible on the outside of the original coils, and used on the copper wire itself as well, has a restricted life. Its a natural product which has been around for over 3000 years! basically as varnish to coat all kinds of materials.
It will be reasonable when kept in the cold all the time, but that is not a realistic condition. Most coils will have become warm in their life and with that the Shellack degrades. A tell tale for a coil gone "to meet its makers" is that it feels a bit "soggy"when you pinch in it.

A good coil with a chance for being still working, should feel rock hard. Most coils however feel soft, indicating that the Shellack has deteriorated and partly migrated from the place it should be. In some magneto's you can even find blots of shellack sticking to various parts of the static internals of the magneto, where it has become so soft it was thrown from the rotor.

Another tell tale of a bad coil is that a motorcycle starts OK when cold, but becomes very hard to start when hot. Due to the softening of the Shellack, windings short circuit and thus reduce the "power" being generated in the coil leaving a weak spark to do the job.

There is only one cure for this and that is to have the coil rewound. Nowadays that is done using very good temperature resistant epoxy resins virtually making them indestructible for the rest of your life.

During the rewinding, its alo best to replace the Condenser/Capacitor in the rotor as well.
These were also never designed for an eternal life and although they might still work, you have more certainty by replacing them with more modern equivalents.
A faulty Condensor/Capacitor is indicated when there is a large spark coming from the contact points, and this mostly accompanies a rather large damaged/eroded spot on you contact points. The spark between the contact points should just be a tiny and hardly visible in daylight.
 

IGNITION TIMING SPECIFICATIONS

The ignition timing settings are a bit confusing. Depending on the source there are rather different specifications.
E.M. Franks book  "Norton" first published in 1948 gives a timing of 3/8 inch (9,53 mm) before TDC.  Motorcycling Maintenance series Norton Motor cycles 1928 - 1955 gives a timing of 7/32 inch (5,6 mm) for period of 1928 to 1937 and of 7/16 inch (11,11 mm) from 1938 upto 1954. The military M&I manual gives a timing of 7/16 inch as well. 
Having had the M&I manual almost from the beginning, I have always used 7/16 inch value, and it seems OK for me.
This all shows that the actual timing is less precise then some people think it to be. Its my guess that this is basically because it is a mnaully controlled operation. A precise setting can be totally ruined if the handlebar control is abused!

 
Setting of ignition timing:

Here you can find two ways of ignition timing. One as given by Lex Schmidt and based on years of experience, the other the original factory proposed way.  Its up to the reader what to follow.