The Pre-1941 Triumph Motor Cycle Pages

From Peter Cornelius - Triumph Specialist for the VMCC - of Britain.

The following is intended for those who have no previous knowledge or experience of Veteran or Vintage motor cycles.

Select or scroll down for the topics below -

Early Engine Types

The very early bikes, which of course started as engines attached to strengthened bicycle frames, had a straight belt drive from the engine to the rear wheel, hence the need to push in order to start the engine, and then jump on before it ran away.
Later, clutches were designed to fit onto motor cycles, and in Triumph's case it was a 49 plate, metal to metal, clutch built into an enlarged rear wheel hub. This was a big step foreward, for it was then possible to start the engine by means of the pedals while the bike stood on a stand. Once started and off the stand, the clutch could be released in order to move off. At a road junction, or whatever, a depression of a foot pedal and the bike could be stopped, but with the engine still running 'freely'.
Hence a 'Free-engined' model, and by default those without a clutch became 'Fixed-engined'.

Early Engine Lubrication, or 'Total Loss' Lubrication

Occassionally I have been asked how the oil is returned to the oil tank, or compartment in the case of a flat-tank machine, as no return pipe was obvious. The easy answer is that it doesn't!
Prior to Triumph's new 1929 C-Series models with a recirculating oil system, oil was not returned to the oil reservoir.
Well before the invention of the 'infernal confusion' engine it had been recognised that lubrication was required in an engine, and oil in the 'sump' of a powerful steam engine was fine, but too much oil in the crankcase (sump) of a relatively low powered motor cycle engine just causes so much drag on the flywheel that the engine becomes very difficult to start, and the power which should be used to propel the bike is wasted in simply keeping the engine rotating.
The simple answer was to simply have sufficient oil in the crankcase to splash around so that the big-end was lubricated and hopefully some found its way onto the cylinder barrel and piston rings. However, some gets past the piston rings and is burnt off along with fuel in the cylinder head; and even more is lost via the primative leather crankcase oil seals. Thus what is in the 'sump' is totally lost, and it becomes necessary to replace it via a manually operated pump approximately every ten miles.
Starting in 1926 with an 'automatic' external Pilgrim oil pump on export Models P (named the Model QA), and internal crankcase pumps in the 1927 Models N and W removed the need to manually operate an oil pump occassionally. However, these pumps simply 'drip feed' oil into the crankcase, and do NOT return any oil to the reservoir. Thus oil is still TOTALLY LOST.
Warning - do not explain this to the examiner at your annual or six-monthly road worthiness inspection, lest you be banned from using such an environmentally unfriendly machine on the road!

Considering that the lubrication is 'total loss' I used to be very neglectful of draining the sump until I had the cylinder off my Model P due to piston problems and discovered what an awful lot of black 'crud' and 'grit' there was everywhere. I now believe that it pays to drain the crankcase at the end of the riding season, and recharge with four pumps with the auxilliary hand or foot pump.

Manual Control of the Ignition, and Timing

If you are coming from a modern bike to the Veteran, Vintage or Post-Vintage (in fact up until about 1955) scene you might not even be aware of the control of ignition timing, for on a modern bike it will be automatically taken care of electronically.
The fuel and air mixture does not 'explode' in the cylinder head, it 'burns', and in doing so expands; thus pushing the piston back down the cylinder. Although it happens quite quickly it actually takes time for the mixture to burn. WHEN it is necessary to start the burning by means of a spark at the so named sparking plug depends upon the speed at which the piston is moving towards the top of the cylinder. The faster the piston is travelling the sooner the spark needs to be fired (advanced), while if the piston is travelling slower the ignition spark needs to occur much later (retarded).
Therefore in normal running on the road the ignition should be set at 'full advance', while when pulling up a hill the speed will naturally drop off, and the ignition should be retarded slightly. By how much will depend upon the severity of the hill, the engine and its age; and experience will be gained by the rider as to just how much retard he will need, and when to start applying it.
Note 1 -
The engines of those days, as opposed to modern designs, ran at low revs, but high torque, due to their long strokes. Therefore on a slope or hill do not attempt to change too soon and rev. the engine in a lower gear. Simply retard the ignition slightly and 'plod' more slowly up the slope or hill. It might well seem to the inexperienced that you are going to knock the big-end out, but the engines were made for this kind of treatment. When you really start to slow and the engine is obviously beginning to labour, THEN change down. As the road levels out again change up and gradually advance the ignition to resume normal riding conditions.
Note 2 -
The fuel of today (so called 'petrol') is VERY different to that which was used when these bikes were new, so burn rates are very different. There is really no point in setting the timing for the value/s given in instruction books. Personally I set the ignition timing so that it is at full retard at Top-Dead-Centre on the firing stroke. No further retard is ever required, and this means that the control is then all-advance, and the engine will let you know if you are over-advancing.
My method of doing this is to set the advance/retard lever to full retard, remove the spark plug, slacken the magneto sprocket, set the piston to TDC on the full compression stroke (both valves closed), set the magneto to the point where the contact breaker points are just about to open at the rise of the cam, and resecure the magneto sprocket. (In case 'things move' while tightening the magneto sprocket, turn the engine over on the kickstart and then check that all the conditions above are still correct.)
To check for a spark (easiest seen in the dark), rest the spark plug on the cylinder head in order to complete the circuit, and on half-advance, see if you have a spark when you kick the engine over. If you don't have a spark the chances are that the magneto needs to be remagnetised and possibly rewound. Most starting problems are related to the magneto.
Note 3 -
As the fuel is now so different to that when the bikes were made do not expect to obtain the fuel consumption figures which were obtainable in those earlier days. You will now be lucky if you can obtain 60% of that you might read of in early magazines.
As we need a fuel as close as possible to the low octane available when these bikes were new, use the lowest grade you might now be able to obtain. The addition of up to one-eighth of paraffin/kerosene will reduce the octane further and give a softer note to the engine. It will not affect the ease of starting.

Acetylene Gas Lighting

If you have acetylene gas lighting fitted, the gas is generated from carbide granules placed into the 'generator' and water is dripped onto the carbide. The generated gas has quite a distinctive smell, and is lit with a match. Occassionally a jet might become blocked and this is cleared with a 'pricker' which is really just a strip of aluminium with a very fine wire attached for pushing into the jet.
Unlike electric lighting the gas generation, once started, cannot just be switched off. In my cycling days I had a friend with such an acetylene front light. It gave a white and very bright light compared with my electric light, but it was strange when he would leave the bike lent against the wall outside a transport café and the headlamp still blazed away until we had finished our beans on toast and were ready to depart.
Acetylene lighting remained popular long after electric lighting and magdynos became available, because few understood how electricity worked. A failure of acetylene gas was easily detected by the lack of smell, and the use of the pricker usually fixed the problem. But you couldn't smell, "that there modern 'lectric stuff, so 'owd you know 'ow to fix it?"
Personally I wouldn't use acetelyne gas lighting as following an evening run in Britain a club member left the pub following his acetylene light. I learnt later that somewhere along the way he had 'dropped' his bike and when fuel ran from the tank ignition followed, and the bike was burnt out.

Early Brakes

From very early days brakes were not particularly impressive, and bearing in mind that until 1930 the British speed limit was 20 mph they probably didn't need to be, although in Britain it had always been mandatory to have two independantly operating brakes (although not necessarily on different wheels).
For many years the front brake was just a slightly grown-up version of the pedal cycle 'stirrup' brake. Triumph's rear brake initially operated on the outside of the drive-belt rim, and then onto a special brake rim when the 'free-engine' came along.
The biggest advance on the rear brake came when the braking medium was pushed INTO the rim. instead of pressing onto the outside. Actually this made/makes a quite effective brake due to the diameter of the brake rim, or 'dummy belt rim' as it is often known. For this reason bikes were ridden with the rear brake as the main brake. (Forget the 75/25% dry, and 50/50 in the wet, which we used to teach on the training schemes, for with no telescopic forks to depress and much lower speeds the transfer of weight to the front is insignificent.)
For this reason it is still a good idea today to consider the rear brake of these older machines as the main brake. You will soon learn braking distances using just the rear brake, but I still keep a couple of fingers around the front brake lever, for although not nearly as effective as the rear brake the five feet (?) it might shorten the distance by could be just what you need should the road junction come towards you faster than anticipated or the vehicle in front brakes without warning.

Beaded Edge Tyres

As the name implies beaded edge tyres were different to the later, more common 'wired on' type. Apart from requiring a special wheel rim to accept them, and being very difficult to fit, there is nothing very special, except for my reason for adding this item to the page - they do need a high pressure in order to ensure that they stay securely fitted to the rim.
The recommendation was for 30 pounds per square inch in the rear and 25 pounds for front and sidecar, but it is not critical.
I rode a whole day, including bouncing over a five track railway crossing, on a Model P I was loaned for a rally over here in New Zealand before we came here to live, and it wasn't until the next day that I discovered that as the bike had been for some time on display in a museum there was only 15 pounds pressure left in the tyres. I was told that I, "had been lucky that the tyres had stayed on the rims."
The introduction of the 'wired-on' tyre was beneficial, not only because it was easier to fit onto a rim, but the lower pressures gave a more gentle ride, when bikes had little in the way of meaningful suspension.


I use the lowest grade of 'petrol'. I add anything up to 1:8 paraffin/kerosene mix. (That's the old 1 pint to a gallon measurement, and being old fashioned although I have to buy in litres conversion to the old imperial measurements are more meaningful to me.)
For a run I usually fill a bike's fuel tank from a container before leaving home. That way I can add the paraffin/kerosene and have a full tank of the mixture from the start.
Even with a 1:8 mixture I experience no problems with starting the engine. I have a half-pint can of paraffin/kerosene in the basket on the rear carrier for adding when I refuel on the run. (As I live away from the main centre I generally covered something like 125 miles by the time I return home, and the flat-tank of the Model P won't cover that distance without a top-up.)
If I refuel and my paraffin/kerosene can is empty I definitely notice how much 'rougher' the engine sounds.

There has recently (late 2008) been in an MG club magazine an excellent article by someone who has conducted some very technical tests on a rolling road in England with his 1949 MG TC car using paraffin/kerosene to 'petrol' mixes as high as 1:5. His more technical findings are worth mentioning and support my 'on the road' non-technical learnings. There have been suggestions that some paraffin/kerosene in the fuel will remain liquid, make its way past the rings and dilute the oil. There was also a suggestion that as there is a percentage of water in paraffin/kerosene this would remain in the engine and cause rusting.
Such suggestions are just 'scaremongering' as far as I am concerned, for the heat of the engine would soon evaporate any 'water' and in years of use I have never experienced any effects of 'oil dilution'.

As a final note, I understand that in order to mix paraffin and 'petrol' legally in Britain a Concession is required from Customs and Excise. Apparently this is easy with a letter to - The request is for a "General Licence to mix hydrocarbon oils under Regulation 43 of the Hydrocarbon Oil Regulations 1973 (SI 1973/1311)", giving your name, address, model and dates of production of your vehicle.
Although, all said and done, who knows that you have added paraffin to your fuel for a Sunday afternoon jaunt into the countryside.

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