Because my bike was made in December of '72, is it classified as a 1973 model?
It was made December 197
1 and is a 7
2 model.
The Triumph explanation of "year" is just rubbish English. It is never clear that "year" always refers to the Model Year, never the calendar year - the two "years" are the same for several months, but also they are not the same for several months ...
Also not made clear is otoh, the date code month letter
is the calendar month ...
Triumph's parent company from the 1950's to 1973 was BSA, the Group's financial year ended on 30th June; anytime after that up to usually September, the works changed to making the following Model Year's bikes. Modern automotive industry still starts building for a given Model Year during the previous calendar year for similar reasons the British automotive industry did - among those, most production is/was exported, transported by sea; from the early 1960's, the US was by far British motorcycle makers' biggest market, it was necessary to build up a large stock of bikes in the US over the winter for what could be a short "selling season" particularly in some states.
The first 72 Model Year ("G") bike - T120R HG30870 - was produced during calendar July ("H") 1971. In that model year, bikes coded HG, JG, KG, NG, PG, XG were produced respectively in calendar July, August, September, October, November, December
1971, then those coded AG, BG, CG, DG, EG, GG, HG were produced respectively in calendar January, February, March, April, May, June, July
1972. Btw, model years longer than twelve months - e.g. HG bikes built in both July 1971 and July 1972 - are not unusual; the serial number was contiguous throughout a model year so the numbers on the bikes produced towards the beginning of a model year are significantly lower than the numbers on those produced towards the end of a model year.
Otoh, e.g. in the 71 model year, the first bike - T100R KE00001 - was not produced until calendar September 1970.
see what is called the pilot bulb. Bike came with just headlight shell, rim, toggle switch and 3 coloured warning lights
don't know where this pilot light attaches.
Not your bike's original headlight. Modern copy of the original headlight:-
... bottom right hand corner of the image shows the hole for the pilot light.
As I posted earlier, LED pilot is useful these days. However, if you do not want to change the headlamp, do not worry about the "pilot circuit" (a Red/Black (RB) wire from the bulb to lighting switch terminal #6).
hole in the bottom of the shell that I believe is for the wiring and a grommet
Original headlight shell on your bike had the three warning light holes and toggle switch hole in the top but had three large grommeted holes in the bottom towards the rear for wiring; only one large wiring hole, the shell was fitted originally to a 71-74 Norton Commando.
Standard harness, you will likely find the single wiring hole/grommet is big enough for the wires that enter/exit the headlamp shell; however, that is because the standard harness has a really rubbish large handful of bullet terminals and snap connector sleeves under the tank,
where the wires from the handlebar switches also connect. 'Back in the day', these connections were not reliable long term, because what Lucas had not allowed for was bikes ridden a lot in rain and road spray, spray works its way between the tank and the frame, into the forward ends of snap connectors, corrodes bullets to snap connectors' internal steel sleeves.
When you are laying out the harness, I advise pulling apart all bullet terminals and snap connectors, replacing the connectors with new - even if bullets and snap connectors are not corroded together, the connector steel sleeves have been under tension for years, they split lengthways inside the insulation then do not grip the bullets as well as they should; although held together by the insulation, the bullet-sleeve contact can be intermittent.
New snap connectors available here and I also advise
this tool for pushing bullets into snap connectors fully, so the latter's insulation covers the bullets as well (as it was intended to do
).
If you need new bullet terminals, British Wiring also sell them; however, due to changes between the Imperial sizes of original Lucas wire and modern metric wire, new bullet terminals are a can of worms, I can explain if you need them. but better will be not to need new bullets.
Also try not to be tempted by the red, blue and yellow insulated hardware store terminals. They are not compatible with original Lucas terminals and connectors, have their own problems.
If (when?) you get fed up trying to make the original harness work and decide to build a better one, the correct headlight shell with three wiring holes is more useful because you can shelter the connections between handlebar switches and main harness inside the shell, much more reliable long term.
:-
Thank you but I do not consider myself any sort of expert; on electrics, just someone who is less scared of them than many.
