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The Pre-1941 Triumph Motor Cycle Pages |
The following is intended
for those who have no previous knowledge or experience of Veteran or Vintage
motor cycles.
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'.
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.
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.
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.
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.
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.
Fact 1
- Fuel today is VERY different to what was available when these
machines were new. That's why I don't call it 'petrol'.
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.)
Fact 2
- The fuel is different in different countries. It depends upon
where it is sourced and the chemicals which each country adds before
it is sold. For example, the additive which evaporates at 30 degrees C
and causes so much restarting problems with older cars in Britain,
could not be used in New Zealand, for on many days it would simply
evaporate as we were filling a tank! Hence, although a higher ambient
temperature I have not suffered the evaporation problem with my old MG
as I did in England. (With air cooled motor cycle engines I didn't have
that problem in England, either, but I'm just trying to point out that
the make-up of fuels depend up on where you use your machine.)
Fact 3
- We cannot expect the fuel consumption we might read of in
period magazines, although a Model R owner has told me recently that
he regularly obtains over 100 mpg, but that has not been my experience.
Fact 4
- My 1927 Model P and 1928 Model N de Luxe definitely run
much smoother with paraffin/kerosene added to the fuel.
Fact 5
- I have been using such a mixture for around 18 years in England and
New Zealand with no detrimental effect to the engines.
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.
With mixtures of 1:10 and 1:5 the ignition was advanced by 2 degrees.
(Not a problem for us as we manually adjust the ignition, anyway.)
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.
With a 1:10 mixture there was a reduction of 9.9% in hydrocarbon
(HC) emission from the exhaust and a 25.7% reduction in carbon monoxide
(CO) emission.
With a 1:5 mixture the reduction in hydrocarbon emission was
39.2% and that of carbon monoxide 36.2%.
Paraffin/kerosene has a higher calorific value than 'petrol'.
Thus, a lower hydrocarbon emission indicates that a greater percentage of
the fuel is being burnt. (These exhaust emissions are
not good for the environment, or for the annual/6 monthly vehicle
inspections!)
Carbon monoxide is the result of incomplete combustion and is
caused by too rich a mixture or poor mixing of the fuel and air. Thus,
the significant reductions indicate better mixing of fuel and air, and
subsequently better combustion.
The power to the driving wheels increased by 1.35% with the 1:10
mixture, and decreased by 1.03% with the 1:5 mix.
Although paraffin/kerosene has a higher calorific value than
'petrol' the tests showed that there was a reduction in 'waste heat'
of 7%, and this was the same for both 1:5 and 1:10 mixes. The engine
was observed to run significantly cooler.
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 -
Mr. John Loughney,
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.
Excise, Stamps and Money Businesses,
HM Revenue and Customs,
3rd Floor West,
Ralli Quays,
3 Stanley Street,
Salford.
Although, all said and done, who knows that you have added
paraffin to your fuel for a Sunday afternoon jaunt into the
countryside.