SQ4 - a little investigation

 Of course, a broken motorcycle can’t be left for too long, especially when your daily rider has been persuaded from your grasp.

There were a few problems to investigate, possibly associated:

• There was a carburetter leak, or possibly flooding 
• The battery indicator was showing far too much red, considering the 60 miles the bike traveled yesterday 
• The bike refused to start twice yesterday, needing pushing to the top of a hill and roll-starting 

Putting the CTEK on the battery had it charging normally, but it was very flat:

But why so flat? According to the ammeter, the battery does charge and indeed, it was charging on the way home. I did notice the ignition had been left on as Tom had complained the engine wouldn’t idle and it had died when he arrived. I currently believe this has more to do with the battery than anything else.

There is no leakage from the battery with the engine not running and you can measure normal currents with lights on, though with the LEDs fitted to this bike these are minimal. The ignition circuit draws 400 mA without the engine running - I think it would be a good idea to try this with the engine running.

I've also realised that the red spot ammeter doesn't show very much deflection at all - I calibrated the one on the Huntmaster against my bench power supply and there is a lot more movement. I wonder if the Square Four has a 30-0-30 ammeter.

A simple test with a 35 watt bulb revealed that the ammeter appears to be 15-0-15 - while I was doing this test the multimeter was reading 5 amps.

As a first step towards sorting the fuel leak, I removed the drain plug/main jet holder and finding no new fibre washer of the right size, sealed it with a wipe of Threebond 1215. That fixed the leak, and there is no evidence of flooding. 

Amelia started first time like she always does.

As to the idle, I don’t know yet as I haven’t got it warm enough to close the bi-starter.

Oops

Well, I got out on my test drive, and it feels much happier - smoother, more torque at the bottom end...

Unfortunately, about 5 miles in, a misfire appeared and the engine stopped. Having experienced this many times during the fuel filter saga, I was quick to look for fuel supply problems and cracked the fuel supply banjo to find all was well. The bike started again, only to stop again after about 100 yards - this happened once more, and then I was close enough to push it home...

Charging had looked good on the ammeter from the first day. All the lights worked perfectly, apart from one indicator which persistently rotated around to face the floor, but in general everything had been fine. However today, when I had the bike running again, switching on the lights would kill the engine.

The Lucas C35SD gives 70 W at about 1700 rpm which equates to 32 mph in top gear, but when you are running around town the ignition, brake light and frequently used indicator loads soon drain the battery, which appears as a fuel-starvation-like misfire. I cursed that fuel line again until I realised what was going on, and a CTEK battery charger came to my rescue. Actually you need about 20 W for the ignition alone, or about 3 Amps; in top gear, you get 3 Amps from the generator at an average of 23 mph – these bikes are really not for town use.

My 1951 Mk1 has a 20 Ah battery bank hidden in the Lucas GU11E style fibreglass box. I'd be surprised if you could even get to the shops with the earlier small battery...

Battery Carrier

This is about the carrier I am using to mount my gel batteries. Here are the batteries:

Now these will happily fit in the box, indeed they were chosen to do so. But because they are so short they will be a pig to get out, and I want to hide a fuse box and maybe some other wizardry in there. So, I have come up with this:

It's a simple carrier made from 18 swg cold rolled sheet; the batteries enter from one side and it is lifted out of the battery box by the two handles on top. The top deck is to carry the fuse box. I plan for the cables to exit through a slot in the upper inboard edge of the battery box:

So, now I have identified where the cables are going, I can cut a slot in the box. A coping saw and a half round file does the job nicely:



So next, final wiring and painting. I have used closed cell neoprene foam to cushion the batteries; painted with U-POL etch primer and black gloss, and wired in accordance with the diagram on the wiring page.

All that remains is to put the lid back on and look at sealing the lid.

Batteries

As I've mentioned before, I have a very nice GRP battery box from Draganfly, made to look like a Lucas GU11E battery. Here it is:

Now, the original GU11E apparently has a 20 Ah capacity, which is the peculiar way in which our industry has chosen to illustrate the energy capacity of a battery - it means it is capable of delivering a current of 20 Amps for an hour, or 40 Amps for half an hour, or 10 amps for 2 hours - you get the idea.

Now an Ampere, or Amp for short, is a unit of current, and current is the rate of flow of electrical charge - measured in coulombs. So an Amp is a way of describing coulombs per unit of time - 1 amp represents 1 coulomb per second of flowing charge. So, if you multiply Amps by time (As in Amp x hour = Ah) , you get back to charge again - and units of charge are what is stored in our batteries.

So, in order to get my bike to run for a reasonable period of time without being charged (for when I choose to ride at 10 mph in a traffic queue on the M25 (when did you last see a Square Four do that?)) I need a battery of sufficient capacity to deliver sufficient current for the time I am riding so slowly that the battery is not charging, without running flat and bring the bike to an undignified halt.

You see, according to this chart I draw from the data in the C35SD dynamo instructions combined with some details of the Square Four's performance (and assuming the C35SD runs at engine speed, which it does, more or less) the dynamo does not start charging until you are moving at about 20 mph. So, go slower than this and the battery is draining.

But how much current do I use? Let's work it out:

• my headlamp will use up to 55W, which at 6V needs just under 10 Amps to deliver the power (Power, W = Potential Difference V x Current A)
• my tail lamp will use 5W, which needs another Amp
• Lets assume the ignition coil will need 20 W, or about 3 Amps

Which gives us around 15 Amps, allowing for infrequent use of the stop light and horn. A 20 Ah battery will be flat in 1.334 hours, or 1 hour and 20 minutes. Reasonable? Lets hope so.

So we know what we are aiming at - a 6 Volt battery with capacity of around 20 Ah that will fit in my neat little fibre glass box. Since a year or so into having the Bantam, Beattie has been using a sealed lead-acid battery - the electrolyte is treated to form a gel, so it can't flow out, and the chemistry is altered somehow (I'm not that clever) so that when the battery is charged and would normally produce free oxygen & hydrogen, the gases recombine as water, replacing the lost liquid in the cell. This is really neat for a motorcycle, because it means you can fit them wherever you want (they are really small), they don't drop nasty acid all over your bike (how many rusty battery carriers have you seen?) and because they are made for things like burglar alarms, they are really cheap.

The downside is you cannot abuse them as you can a traditional wet battery - if you overcharge them and lose the electrolyte, you can't replace it.

The thing is, I came to use one of these things the first time because I realised the rudimentary (putting it kindly) charge control system on the Bantam was boiling the original wet battery - so I added a modern solid state regulator/rectifier (from the marvellous Rex Caunt Racing) and was able to use a gel battery. The one on the Bantam is tiny - about 3.4 Ah I think, at 12 V, and has coped perfectly for several years. It even remains charged through the winter, something the old wet battery could never do.

Coupling Gears

Things are moving on... Not much progress lately, because despite the fact that I am not at work at the moment there is a house to be refurbished and summer weather to be enjoyed! Plus, I have a little Off-Grid Garage project to tell you about later.



So, bottom end is in and now we can fit the coupling gears. Easier to do on the bike, since we will be heaving the cranks about and we don't want the engine moving about.



Here is the coupling gear 'pusher' tool, supplied by Drags, and an essential piece of kit. It has two large adapter nuts each with two threads - one for the pusher rod, and one for the crankshaft. You'll note that the threads on the cranks are different, hence the need for two adapter nuts. At this point, you will have the Woodruff key in place, and the coupling gear keyway aligned with the key. You won't be able to see it in a moment!

The pusher tool is actually a puller, since it pulls the crankshaft into the coupling gear. You need the coupling gear puller to go with it. The puller is assembled onto the gear - and now you don't know where the keyway has gone... Grease that pusher rod thread (to avoid it galling) and start turning - you will need a significant torque and you will have to lock the crankshaft using a bar through one of the rod small end eyes. Use two timbers to prevent damage to the crankcase mouths. Oh and a word of warning - do not swing the crankshafts about without the coupling gears fitted. The rods WILL hit each other and you don't want any nasty dings.

You need to make sure the coupling gears are properly aligned. The gears will only go onto the crankshafts one way, and there are dot marks to align the front and rear cranks properly. Align the gears so that the tooth marked with one dot meshes between the two dot marks on the other gear.

Whilst the coupling gears are identical, one of them will be marked 'F' for 'Front'. Fit this one at the front, and you will maintain the wear pattern established when the engine was last running.

When you are done, fit a new oil seal to the rear crank and do up the nut on the front crank.

Next, trial fit the coupling gear cover. No bearing in this one yet, but those studs are in two different lengths. The long ones pass through the dowels at 3 o'clock and 9 o'clock.

Then the primary case inner:

Then the outer, tensioning the sidestand spring

Then you find the clutch cover screw holes are stripped, and that's why we do trial fits!

Then the battery carrier. The shiny fibreglass battery is going to need some matt black paint and a spray of oil or WD40:

Looking good isn't it!

Apologies...

Apologies if there doesn't appear to be much going on, but I have been away travelling again. Last week was spent mainly in Stavanger (-7 degrees C) and Oslo (-18 degrees C) and I have only just thawed out.

When I am away working, I tend to order stuff to get busy with when I get back. This was a similar trip. I have been talking to Bernard Ashpole in Bishops Stortford about doing a few jobs on the engine. I'm going there tomorrow and hopefully the following jobs will be done:

• soda blasting the crankcases, barrel and the original head (so I can sell it)
• welding up the damaged fin on the barrel
• replacing the timing side main bearings, line boring them and replacing the camshaft bush
• tidying up the camshaft journal

I ordered the dipswitch, horn button, and the indicator switch from the VMCC - these are now stashed away. I also ordered the oil filter, which I have to make a bracket for. I'll zinc plate that when I'm done.

I've also ordered a few more parts from Acme, this time the exhaust brackets & bolts and the 5 nuts for the QD rear wheel, and the front brake cable adjuster.

I have a full set of stainless engine bolts from them, and the timing cover, primary cover, and coupling gear cover screws. All very nice, as usual, and a pleasure to deal with.

When I ordered the camshaft bush from Drags, Lee noticed that I had a battery box (the dummy Lucas GU11E) on back order - so this has now been delivered. Here it is in the tray I made earlier. 

And lastly, I have been looking at the wiring. Moved by a discussion on cable ties on the AOMCC forum (how many rivets in a BR Standard Class 5?),  I started to look closely at the wiring harness.

This discussion was so interesting that I have moved it to it's own post, here

Back in Charge

As an aside from the engine strip, which is challenging at the moment since Amelia is still resident in the Summer House and the bottom end is in the frame, and there is precious little light to use to continue the engine strip, I have been polishing up the chain case and making the battery tray.

You'll have seen the post Battery Carrier earlier in the blog and you will know that I had no part of the battery carrier originally. You'll also know that thanks to the generosity of the Ariel Owners Club members I have been able to get all the technical details I need to make one.

So, starting with Brenton Roy's drawing, the dimensions of the GU11E battery from an old Lucas catalogue and some 16 SWG cold rolled steel sheet, we could get started.

Using the faithful Bosch jigsaw, I cut an oversize blank just to have something I could handle on the bench. These days, having failed to make myself some engineers marking blue, I mark out using a Sharpie spirit marker before witnessing in the traditional way, with a dot punch.

The next stage was to cut out the shape with the hacksaw. The 'internal' tabs (those that the screws pass through, underneath the battery carrier) I cut out with a piercing saw, starting first with a 1 mm drill at each end of the cut. 

The shape was then finished off with various files.

The holes were then centre punched and drilled 7 mm, (clearance for a 1/4" BSCy screw).

The next stage was to fit the nuts. These were 1/4" BSCy full nuts, tacked in place with the trusty MIG, and yes, those holes are noticeably triangular - hard to drill perfectly round holes in sheet metal.

The next step was to bend up the tabs. I put both halves of the chaincase in the vice to check the overall width before I did this - I didn't want to end up with the tabs out of parallel or rebending them.

Here is the raw battery tray fitted to the chaincase for the first time. The special fasteners and spacers are from Acme Stainless. It's looking good.

That is about it really. I re-cut all the threads since the welding appeared to have caused a little distortion  I draw filed the edges and deburred, and since this picture was taken I bent up that tabs that retrain the battery. Might be a problem here - I have ordered a battery from Drags but I don't have it yet.

Last thing before assemble was to paint - the usual UPol etch primer, followed by Halfords gloss black acrylic, then final assembly, and that's it. Again, stainless parts from Acme.

A few days spent in a warm room saw it packed away in a box until the bike is assembled.

Battery Carrier

Amelia is completely devoid of any battery carrying facilities. She should have the big Lucas GU11E battery that appeared in 1951.

Thanks to Brenton Roy & Guy Rayner of the AOMCC for these images of what I need to make, find, swap or a combination of the three:

What I need is the dimensions of this part. Anyone measure one for me?

Underside, showing the screws that clamp it to the primary cases.

Here is the strap, best English chrome plate, available from Acme Stainless in a rather more appropriate material.

And here is the large battery carrier, in position on Guy's 4G. As he says, his bike should have the small battery. Alas I don't have one to swap...

As a postscript to this request, the ever helpful Brenton sent me this:

We'll be making one of those later.