Oil Tanks
The Mk 1 KTTs had a different oil tank from the other Mk 1
OHC Velos. The 2 main differences are that the filler cap is on the left side
of the bike and provision of a much larger oil tap. The oil tap allows a 3/8” inch
bore feed pipe to be fitted and this, in turn, gives a reduced flow restriction
for the gravity-fed oil into the engine to the upstream side of the pump compared to a more common smaller diameter pipe.
The picture below shows the 2 original KTT oil tanks to be
fitted to KTTs 55 and 305 whilst the other tank is a standard oil tank that
will be fitted to the cammy special. The standard oil tank is one of 2 that I
had made in India over 10 years ago and was copied directly from an original
Model K tank that I took out to Bangalore.
However, apart from the obvious cleanup that is required (and that will be done in the "painting and plating" stage of the project), a couple of repairs were needed to the KTT tanks. The
first was to the large boss that supports the oil tap on one of the tanks that
had rusted to an extent that the tap would not screw in. It is a large
(15/16” diameter) 20 TPI thread and rather than buy a threading tap (to clarify use of the word "tap" for non-English native readers of my blog, "tap" has more than one meaning - here there is an "oil tap" and a "threading tap" - quite different things) to recut the thread –
which was pretty expensive and would only be used once, I decided to screw-cut
a male thread on the lathe on a piece of hexagon bar and to use that to gently
re-form the thread in the boss.
Although some slots were cut into the threaded portion (to
replicate a tap) and this approach worked well on a threaded
brass filler for the V-Twin this approach did not work here …it simply
detached the boss from the tank with very little effort being applied!
I suppose that, being an optimist, it is better that this
happens now rather than when the tank is full of oil and on the bike!
Plan B: Make a new one,
screwcut the thread and check the fit with the oil tap while it is still in the
lathe
carefully clean up and tin the mating surface of the oil
tank and the new insert and soft solder the insert into the bottom of the tank.
These tanks are constructed entirely by soft soldering and
soldering the new insert in place has to be done very carefully to avoid
un-soldering other parts of the tank.
I can’t remember if I mentioned this before, but my powder
coater told me of a customer that brought along a 2-compartment (oil + petrol) flat-tank
from some vintage bike to be black powder coated and, in spite of being warned
about the temperature used in the baking process (around 200 0C),
ended up with a pile of sheet metal and a large blob of lead. A salutary tale!
The oil tap itself needed a couple of repairs: first, the
filter had become detached and needed reattaching;
and secondly, the oil tap knob looked like this:
….not a pretty sight!
A new knob was made in 2 parts, namely a steel centre that
has a square hole in the centre (filed to shape rather than spark eroded) to
fit the male square on the end of the tapered portion and with “bump stops” for
the fully-open/fully-closed positions plus a brass lever, which was machined
out of a piece of square bar on the milling machine.
These were silver-soldered together to make a complete and
well-fitting oil tap knob.
Last, but by no means least, new viton seals were fitted to
both of the filler caps.
Steering Locks
In my
last blog I mentioned that I had made steering locks but that I planned to
replace one part, the head steady clamp (KA-43), that I had used with a
modified version that was threaded. I had made a pattern for this by adding a
boss to an existing head steady clamp and, together with patterns for saddle
clamps (KA-111), these had been taken to the
foundry for casting.
These were cast in HTB3 – a high tensile brass. This
material is remarkably strong with a tensile strength quoted as 740 N/mm2
(see, for example, here).
This is in the same range as EN8 steel and more than adequate for these
components.
This is the collection of castings that came back from the
foundry.
After tapping a 5/16” BSF thread into the boss of 3 of the
head steady clamps I now have 3 steering locks as shown below.
One of these (upper right in the above picture) is narrower
and shorter than the other two because I had to modify the design when I ran
out of square alloy bar. A couple of people that read my previous blog
contacted me and asked for the dimensions and so I have annotated a photo,
shown below, that should be sufficient to make one.
The dimensions in the picture above are for the smaller
design because I think it is actually an improvement over my original version.
Saddles
In the 1930 Velocette KTT brochure the saddle fitted is
advertised as “Lycette Aero Elastic, three-point adjustable fixing”. I have a
number of Lycette saddles in my “store” but all of the stem-fixing design – the
type that is supported on a tube that fits into the rear frame tube.
However, I do have a three-point fixing “WRIGHTS” saddle in
excellent condition that, with a swap of a badge, will morph into a Lycette
saddle.
The saddle that came with KTT 305 was a Dunlop “Drilastic”
and the cover was in very poor condition
Luckily, reproduction Dunlop covers of this size are readily
available. These are advertised as the “small” variant here in the UK and this turns out,
as far as I can determine, to be F89/4S in the Dunlop advert – see below – I had
already fitted one to the AJS 33/7 in the last restoration (see here)
and although they are a bit tedious to fit – the cover needs riveting to the seat
frame, these saddles are quite straightforward to restore.
The other 3-point fixing saddle that I had was another
Dunlop “Drilastic” but a larger size. It turns out that these were made in 6 different
sizes (!!) as shown in the 1931 Dunlop brochure below.
Acknowledgement to Dennis Quinlan from whose blog this
picture was taken. See here
for an exposition on early saddles.
The picture below shows the original larger saddle, complete
with its frame.
This identifies as F69/4D in the Dunlop advert and I found
it impossible to source one of these in the UK. Luckily, I found what appeared to
be the correct saddle on the website of a French motorcycle dealer and,
although the dimensions given on the advert were incorrect, it appeared to be
the correct size that I determined from the ratio of the length and width. I
ordered one and it fitted the seat frame perfectly.
It has a different surface finish on the top
and, as can be seen in the picture below, the smaller seat
cover actually fits inside the large one.
The next detail to be resolved was the “DUNLOP” badge on the
back of the seat - the seat is really not complete without this.
I tried using letter stamps of the appropriate size on a piece
of brass strip but this looked pretty crude. Eventually, I found an online
engraver that could produce a pretty good approximation to the original – the picture
below shows an engraved and blacked badge compared to the embossed original.
I figured that this would be about as close as I could get to
the original and after powder coating the frames
buying another batch of bifurcated copper rivets and
annealing them
I fixed the badge to the covers and the covers to the frames.
The picture below is the smaller cover compared to the one fitted to the AJS
with an original badge.
The new badge is a bit shiny but I’m sure that can be fixed!
The picture below shows the smaller saddle on KTT 305. It is
important that all rivets, front and rear, as shown in the advert, are used to
ensure the cover is properly secured and does not “tear away” from the frame.
The castings for the front saddle clamp have not yet been
machined and I’ll get to that in the coming weeks.
