FH - pilot circuit

 No pictures, but this afternoon I've drilled out the fixed size 20 pilot jet in the Huntmaster's MK1 Concentric carburettor.

It's now got a size 30 pilot fitted, which reflects the size 35 specified for the BSA Road Rocket (fitted with a Monobloc) and the fact that Concentrics are supposed to run richer than Monoblocs...

Time for a road test.

Model A - rear brake pedal

 The rear brake pedal shaft is one of those areas where you see the horrors perpetuated on old motorcycles through years of neglect and changes of ownership with varying levels of skill. Having removed this one to rebuild the footrests and replace the brake pedal spring we realise that it is in fact a bit mangled.

To start with, we can see that the thread has been cut to a BSW form - Ariel would not have used BSW here, the thread would originally have been CEI. We will build it up with weld and cut a new thread to the right size.

That pin across the right hand end as we look at it forms both the stop and the fixing point for the end of the spring. Part of it, the fixing point for the spring, has broken off. It proves impossible to knock out though it is listed in the parts book as a separate component, so we drill it out.

Here it is, illustrated in the 1930 parts book:

The other curiosity which I didn't understand initially is how the shaft is lubricated. There was no obvious grease nipple but under all the gunge a hole appears half way along the shaft, which is clearly to let grease into the central reduced area - and an ex-nipple on the end which has had some attention from a hammer.

I've said many times that the AOMCC is a wonderful club to be associated with and a few questions posted on the Facebook page yielded this drawing from 1925 and signed by Val Page himself. The drawing clearly shows the same formed nipple on the end of the shaft that the later Ariels used until the end of four-stroke production in 1958.

The difference between this and the later bikes is that whilst the later bikes use a nut to retain the brake pedal on a parallel fixed shaft, this application uses a nut on a taper to retain the pedal on a rotating shaft. Therefore when you want to remove the pedal for adjustment, you have to undo the nut and knock the end of the shaft to free the taper. Guess what happens? The nipple gets flattened...

To start with we're making a new pin on the lathe. I didn't intend to use a piece of stainless, but at the time I couldn't find a quarter inch piece of mild steel round bar - but no one will ever see this, so it doesn't matter if it's the wrong colour.

I've cut a semi-circular channel in the end of the short bar to locate the brake pedal spring. It's a simple matter to chamfer both ends and press it into the pedal shaft.

This is how it looks.

This is apparently the correct spring - I got it from AOMCC Black Ariel spares some while ago and I'm assured it is the right one, though it looks very stretched when it's in position.

See what I mean?

The next step is to build up the mangled thread and nipple. This is none too tidy but hopefully there will be enough material to turn it to 7/16" without firing up the TIG set again.

The first pass at turning to size shows, as it often does, that more building up is required:

That done, we can start forming the shapes according to the drawing with a radius tool to form the curve and shape the grease nipple:

I seem to have missed out a step here - I've forgotten to photograph the drilling out of the grease hole, which is 5/32" per the drawing. The next step is to cut the 7/16" CEI thread. 

Here it is on the bike with the brake pedal attached:

We will need to be very careful when moving the pedal - using a socket or something over the nut to avoid damaging the nipple!

Mini-lathe - angle plate

 Some while back we looked at an arrangement to use the compound slide vertically to cut some slots in some screw heads. At the time I had this angle plate with a shim to put the compound slide exactly perpendicular to the bed. 

Now that I have my MIG welder working again I have overlayed the angle to some extent and I'm using a fly cutter to create the perpendicular surface. It looks horrible at the moment because I did the overlay with the MIG at night, with the inverter protesting at the low voltage.

I've made a couple of passes with the fly cutter and we can see where the welding is low.

We will do some more passes with the fly cutter and then fill in some of the holes.

Meanwhile, we need to make this angle plate as stiff as possible so we will put a brace in each end:

One of the functions of the angle plate is to carry the rotary table. Whilst this has its own 90° mount, it takes up a lot of space and for the purposes of the kickstart shaft we would have to extend the cross slide considerably to get it in the right place. A better alternative is to use the angle plate to mount the important part of the rotary table like this:

We will progress the rotary table mounting a bit further when we have finished making the back of the angle plate flat:

Flat, cleaned up and almost finished. The surface is perpendicular to the cross slide top!

There's a couple more bits to do - I'd like to take an end mill to that bottom edge and tidy up, and one of the rotary table holes needs elongating for adjustment. I'll do that when I set up for milling the kickstart shaft.

Model A - kickstart shaft

 We're making chips! After a few test cuts, I've settled on a spindle speed of 750 rpm using carbide with oil mix cutting fluid and I'm getting a great finish. 

Depth of cut is 0.5 to 0.75 mm, and the feed is probably something like 0.002"/rev. The lead screw gives you 0.004"/rev and it's much slower than that, but unfortunately I have to manually feed at the moment.

There are a couple of upgrades you can do to reduce the feed rate, but they both need 3D printed gears which I don't have...

FH - not charging...

 Having learned that the FH will drain it's oil tank through the gear pump into the sump, I try to run it once a week or so during the winter. It was on one of these occasions that I noticed it wasn't charging and my first thought was to look at the dynamo to see if it had broken another chain.

Fortunately not - so I left it alone for a dose of thinking about.

Coming back the next day, I worked through the other electrical systems to see if anything jogged my thoughts and found the rear light wasn't working either: given that the ammeter and the rear light connect through the lighting switch I had a look under the top yoke:

Two wires had pulled out of the five way connector. Harness too tight or connectors not assembled properly in the first place?