FH - Monobloc Carburetter

 I've been toying with the idea of fitting an original carburetter to the FH for a while, and finally bought on on eBay - I actually ended up with two, having bought one, it turning out to be not as described and the seller not wanting it back. That was a 389; I also have the correct 376/12.

Having messed up the 928 by not paying attention (more of that later) I fitted the 376:

It's not in too bad shape. The mixing chamber cap retaining ring is a bit loose, and of course the slide is a bit worn but otherwise it's sound. It's more or less to spec - I can easily modify the #3 slide to a #3 1/2 with a file; I have a close-enough main jet. The 928 that was fitted had a 260 and was obviously 28mm - that's about 1 1/8" which suited the 'Road Rocket' specification to which the engine is built. 

	Monobloc 1	Huntmaster	Road Rocket	Monobloc 2
Part Number	376/12	376/12	376/36	389/12
Size:	1 1/16”	1 1/16"	1 1/8"	1 3/16”
Main Jet:	260	240	290	300
Pilot Jet:	25	25	35	30
Needle Jet:	106	106	106	106
Position:	3	3	3	3
Slide:	3	3 1/2	3 1/2	3

The plan is to see how this goes before we do anything else - it should give me a better base to get the carburation right. Unfortunately I will have to make the throttle cable shorter and the choke cable longer to make this work...

'Do anything else' could mean buying a 928 Premier; it could mean buying a new Monobloc.

And the 928 that came with the bike? It wasn't the Premier, so it had the built in idle jet. I wanted to change the pilot jet size and to be able to clean the idle circuit so I drilled out both the plugs that seal off the idle drillings, re-tapped one M5 and was considering tapping the other one M7, and making a special plug - unfortunately I took my eye off the ball, and thinking if I put the plug further down I could put an M5 plug in that side as well - and drilled out the pilot air screw thread. One useless 928 body, for which you can't get a spare.

Model A - front wheel

One of my key aims is to get the machine rolling so that I can get it off the bench when I need to, to get the others on the bench for servicing etc. To that end I sorted out headstock bearings and the wear in the forks, but of course we still have no tires and the wheels are not fit to have tires fitted.

I thought I would change away from my normal method of dismantling a wheel, involving bolt cutters, and see how feasible it was to dismantle it nipple by nipple. I sprayed each nipple with plus gas months ago and I was pleased to find them all come apart easily.

Before long I had a fully stripped hub and brake drum a pile of loose spokes, nipples and a rather rusty rim - a WM1-20 which might get reused one day if I can ever buy tires for it.

Despite worrying about whether I'd made the right decision with respect to the rusty nature of the rim, the spoke heads confirmed that rebuilding the wheel was a good thing to do. Several of the spoke heads are about to pull out of the hub:

After a short period of decreasing, scraping of general muck and abrasive removal of rust, I put on a coat of primer

Followed by a couple of coats of black gloss:

The black powder coated rims have been delivered from Devon along with spokes and nipples but we will need to wait something like 5 or 6 weeks for this paint to harden before we can build the wheel. More of that later!

Model A - dynamo drive

 I have been wanting to sort out the dynamo drive for a while - not having it in place leaves a lot of parts laying around on the bench that I want to clear up. It was hindered by having to make a special puller for the dynamo bearings, something that I use infrequently but is very necessary if you're going to rebuild one of these dynamos.

Having finished the puller, I spent a little while turning up a short spacer. For some reason the replacement armature is a little shorter than the original though it fits where it needs to!

And I needed to file up a Woodruff key for the dynamo drive sprocket. It actually took me a long time to get to this place because I had inadvertently assembled the dynamo and fitted it with the dynamo body the wrong way round which caused the sprocket to be something like a half an inch out of line!

Here's the drive in place

That was a chain in amongst the past that came with the bike - is the correct 3/8 inch pitch but the width is way too much. I'll have to look at simply bearings and see if I can find another one, but it really needs to be endless.

You can see here that this over wide chain will rub on the crankcase.

The thickness of the drive sprockets is 1/8" - so that tells us what chain we need.

Mini-lathe - front stay spacers

 The mini lathe proved its worth again today and gave me two useful parts from some scrap.

These are 3/4-in diameter by 3/16-in thick spacers for the Model A and the W/NG, with 6.5 mm holes to clear quarter inch screws.

Here is where they fit - what they do is give you a little bit more room between the fork leg and the mudguard stay to stop the brake rod rubbing.

They will be chemically blacked in the next batch.

FH - insecure centre stand

 Some while back I wrote about adjusting the stops on the centre stand to get the wheel off the ground and to enable the bike to roll on and to roll off the centre stand relatively easily. A few months using the bike has made me realise that it's far too easy for the bike to come off the stand and since my son has had it he's remarked on it a couple of times.

I need to do something about this. 

I recall that when I bought the shock absorbers I was encouraged by fellow riders to go for a longer shock absorber option to make the bike easier to get on and off the stand, which it does. The bike is actually fitted with 310 mm shock absorbers - the standard is 300 mm, or more probably 12 3/4".

Stripping one of the shock absorbers finds an M10 by 1.25 pitch thread on the damper. An option would be to increase the length of this thread and then chop the excess 10 mm of the end of the damper rod. This won't be too much of a problem except that I don't have the suitable die and if I can't remove the rod from the damper I will have to cut the thread with the die but leave no undercut which will be untidy. I can't remove the rod from the damper, because the top of the cylinder is rolled over.

My first step was to ask the supplier if I can buy the damper units without the rest of the shock absorber, and these turned up for about half the cost of a new set:

The next step - and it's never straightforward is it - is to modify the spring compressor. The problem is that the compressor now has to reach so far down inside the spring (because the damper is shorter) that I can't get the pin in through the damper eye. 

I sorted that out by chopping one end of the pin off, trimming the end and welding a washer on the end to act as a head. 

Next I rebuilt the shock absorber and then turned my attention to the other. With that done I could remove the centre stand and adjust the stops. There's not much to see with this operation apart from my grubbing knees elbows and nose. Doing this job on the side stand is ok for the right hand side of the centre stand but getting to the left is very difficult, especially when the temperature is in 30s!

I ended up taking 1/16" off both stops which resulted in a bike that needed more effort to get off the centre stand. I noticed that the stand feet are wearing already and will need some attention in the next year or two.

Square Four - another clutch

 Well, I recorded in my last post that the Square Four clutch was slipping badly, so badly that as I rode it up the hill back to the workshop the engine speed was soaring and it was clear that the clutch was on its last legs.

I've said many times before that these bikes are very easy to work on. One thing I've always done when accessing the clutch is removed the footrest - but actually don't need to do that. All you have to do is remove the nut and rotate the footrest on its mounting out of the way - you don't have to break the taper at all.

Even before I dismantled the clutch it was clear what happened - you could smell the burnt cork and there were bits of it everywhere. Stripping the clutch down revealed carbonized cork inserts - I could put my finger through these and they would just disintegrate.

Fortunately I had a spare set of 90 corks - that's enough for three plates - sitting in the workshop. Once I'd spent a couple of hours cleaning the mess off the plates I put these in boiling water for a few minutes.

You can push them in with your fingers - or a bit of wood is sometimes useful. It does make your fingers hurt after doing all of them, but it doesn't take long really.

I thought there was one missing - so I rescued a wine cork from the bin.

It's easy to slice these up into the right shape.

As it happened, as soon as I started clearing up the plastic bowl I've used to soak the corks I found the missing one so I didn't end up using my homemade one.

A couple of hours work had all the plates re-lined.

When you put new corks in, I always fit them to the bike wet. When you initially fit the plates they will only just be retained by the basket slots but the next day you will find they have settled a lot. You can see in this picture that the first friction plate is now well into the slots - this is about 24 hours after reassembling the clutch and all the corks are now dry.

I tested out a couple of days later, and readjusted the cable. The bike started straight away though as normal the clutch was stuck - I have always had to free the clutch before starting this one.

Sheringham Classic Car & Bike Show

 About this time in June, every year, Sheringham hosts the annual classic car and bike show. We've had a wander around most years and the Square Four has been to a few; this year son Thomas came, bringing the Huntmaster back to Sheringham from his garage in the city.

It's time for the 500 mile service and general checkover and the bike appears to be going well.

He says he has a list of jobs for me - some of which I'll do and some of which I'll quietly ignore... 

It's quite mucky and appears to have leaked all of its fork oil over the rest of the machine. It's also smoking as it always has done but that really needs looking at.

He says the clutch is slipping - and it is adjusted rather too tightly. On entering the show the marshals made us ride at walking pace behind a Rolls-Royce Corniche which was quite testing for these air-cooled machines. When it came for departure at 16:00 the Huntmaster started straight away and I rode it home but it was clear that the Square Four clutch was slipping far too much to start the bike. I got the tools out in front of The Crown - the garden was packed full of people so I had an audience as I slackened off the clutch cable. 

Fortunately that was enough to get sufficient torque through the clutch to kick it over and start it - which it did first time. It's slipping really badly and it's clear that it's been too tight like the Huntmaster one and that the slow ride through the town was too much. 

Note to self here - keep enough play in the clutch cable!

Model A - front forks dry build

 You might remember from the recent girder fork investigation post that we had a lot of movement in the forks - in fact a 3/8 inch variation in wheelbase. It was obvious that a lot of this was down to wear in the links and wear in the spindles.

I contemplated reworking the original links for a while but while chatting to the AOMCC Black Ariel spares specialist I discovered that reproduction links were available from the club at a good price, so bought a set. They're not perfect - for example the middle links are smaller in diameter than the originals so I will keep the originals and repair them at some point.

For some reason the top links on the 1929 and 1930 bikes are not fully threaded:

The club spares officer also recommended I bought a new spring. It's certainly true that old fork springs I've used in the past have been very soft and looking at the old spring previously it was clearly a bit stretched. Again new ones are available at a reasonable price:

Putting these bits together with the old spindles revealed a significant reduction in play.

A few days later, the new spindles arrived from Acme Stainless - and very nice they are too. On bikes of this era, you don't need the knurled washers - these arrived in 1934. I bought a pair of headstock nuts as well since I was one missing and pulled up the steering head bearings a bit more. 

Putting all these in place removed all of the play in the forks. I now cannot detect any variation in wheelbase.

Stuck in the steering column there is the beginning of the blanking plug that is used on the Model A which was not supplied with a steering damper.

That plug will be chrome plated eventually. I'll finish it machining it long before that happens!

Model A - magneto

 As usual, I will be using the services of Mr Tony Cooper of Halesowen to rebuild the magneto for the Model A. I spoke to Mrs Cooper today and learnt that Tony would be able to rebuild the BTH KC1 for me. He's done the magnetos for both the FH and the W/NG, and they are excellent - the estimate for the Model A was a maximum of £250 and it would take 14 to 21 days.

This is how the magneto looked when it arrived. It's more or less the right period for the Model A but as you can see it is a slack wire advance magneto - Ariel specified a tight wire advance magneto. In theory, slack wire advance is a better option because if you lose the cable, the engine will still run optimally at speed - but it might be rather hard to start!

First job then is to remove the magneto. Fortunately this side of the engine is relatively clean and it's quite straightforward - it's just the same arrangement as the W/NG, built 12 years later.

Underneath I was surprised to find only two bolts holding the magneto down - the magneto is set up for four bolts, the W/NG uses three. 

With the magneto chain cover removed we can have a look inside for the first time, and it's all pretty familiar and pretty clean although the chain is very loose indeed:

All you have to do is remove the magneto retaining nut and then use the usual magneto pinion puller to release the taper:

You can then remove the two bolts holding the magneto to the platform and lift it out of the way. There appears to be a seal between the magneto and the chain case which looks like it is a felt seal sandwiched between two pieces of tin - it's black and oily at the moment so when it's cleaned up we can have a proper look.

Here are a couple of before pictures of the Magneto after it's had 15 minutes of fame in the parts washer:

Looks pretty good and turns easily. There's something wrong at the points end though - the bolt retaining the points to the armature makes contact with the brass end cover. One of these parts must be wrong, probably the end cover because in this arrangement the magneto will always be earthed and will not spark. 

Tony Cooper will sort all this out!

... 10 days later

It's back sparking merrily with a new armature and slip ring:

The end cover hasn't changed - but it turned out that there was a seal missing which stops the cover touching the point screw.

Model A - front stand

 Whilst working on the forks I made a little side project out of the front stand. Whilst I have the forks in bits I want to make sure that the mudguard and it's stays are all in the correct places, which of course includes the front stand and it's fixings. Sorting that out will also allow me to trim the front mudguard to the right length

We have the original front stand with the Model A, but unfortunately it's rotted out. I always seem to end up welding these stands for one reason or another, and this one is no exception - the stand retaining clip is missing as well.

I've had some suitable heavy wall tube knocking around since the FH project which needed its front stand extending by about an inch. It's a blessing that Ariel didn't change their design every 5 minutes and the stand material used here is the same as is used on all my other bikes - consequently there's about three feet of suitable tube in the material bin that I can use to fix this stand.

I use the Rothenberger Superfire 2 blow torch to make freehand bends using the old stand as a pattern and eventually end up with a complete bottom section that I could weld to the old arms

The linisher is very useful for squaring up joints in tube work which in turn makes a very straightforward autogenous butt weld:

Before we go any further, we need to make the clip at the back of the stand to position it in the right place to get the arms the right length and in the right orientation. This is the clip on the W/NG:

I've made this out of a piece of 16 gauge steel sheet cut to a strip around 1 in wide and I've drilled a 1/2 inch hole in the strip to receive the annular part of the special nut which is used to retain these stands. I folded the strip in half and cut a slot to clear the 5/16 inch bolt to which the stand is fastened.

I made a few of these special nuts on the lathe some while ago, probably for the WNG. The Model A was in the pipeline at the time and I knew I would need a few:

I've used this electronic level and some pictures provided by fellow club members to set the stand in the right place to determine the position of the hole for the clip:

With the hole marked and drilled, and the mudguard cut to the right length, I fixed the new stand section in place with the new clip:

With the bottom section in the right place, I can measure the length of the arms and tack them in place:

It's a very straightforward job which finishes this area ready for paint.