Rings...

So the block is now ready to go on - it's time to gap the rings and fit them to the pistons.

I bought my rings from FW Thornton after asking both them and JP in Australia to quote. I had asked Drags as well, but the GPM rings they supply require the ring grooves to be machined to depth - and wisdom from the AOMCC forum suggests this is not easy.

So, having a modicum of engineering knowledge and some measuring tools, I read up on rings & piston design courtesy of Mr. P Irving's writings and set about sourcing the rings from basic dimensions. Duncan Rowley (who is a very helpful chap) at Thornton's came up with this set of rings from my dimensions:

We have our rectangular top rings:

And our Napier pattern second rings (this one is upside down):

And the oil control rings:

Speaking of which, don't forget to clean out these holes:

These are there to clear the oil which the oil control rings scrape off and return it to the sump.

Tappetty Tap

So we are getting closer to fitting the block and pistons... First job, polish the block.

But first of all, remember that broken fin?

Well, here it is again. It has been built up with weld (small TIG torch) by a very clever man called Steve at Bernard Ashpole's:

And later, having years of cr@p cleaned out of it. This debris has been removed bay various bent wire tools, poking out all the areas between the fins, the pushrod tunnels, and between the cylinders. It's a complex casting, I would love to have seen the core for it:

This stuff almost looks like casting sand...

There is actually a 'ramp' in here, shaped rather like an old-fashioned deflector piston, which deflects air upward towards the head. You are looking from the rear, where the dynamo would be, at the back of the ramp:

And here it is today, polished as it was when it left the factory. You can see the honing marks Ashpole's left:

Next stop, and before I forget to put them back, the tappet blocks. Here is one of the three good ones - one of them came out in several pieces.

Here are two of the tappets. The groove is for a small wire circlip which serves to retain the tappet in the tappet block. This appears to be an assembly aid, since it stops the tappets falling out of the block when you lower the cylinders into place.

Another view of one of the tappet blocks. Curiously, these are plated with something resembling tin? Not sure why. Heat transfer?

This is the new one from Drags:

And this is how you fit them. First place it in position:

Then you can place it's neighbour. Observe that the two flats are facing each other.

Then you can drive them in with a large socket. A little heat helps, or a press - but I don't have a press... So the hammer is always at hand.

When they are in place, you can fit the retaining bars.

With their tab washers & nuts:

Pretty Pretty?

As you will have seen from the recent post 'Phase 2 and wheels', we had left the tank and wheels with John Spurgeon at Aerographics in Horsford, near Norwich.

Well, they are back and what a picture! the tank is like new:

The tank has been blasted and is sound. there is some brass filler from the factory but no corrosion or dents. It has been etch primed, coated in Damask Red two-pack and the lining applied in accordance with some information from the Danish Ariel club website, originally supplied by Draganfly:

I provided the tank to John with the rubbers and badges fitted, and he used these dimensions as a guide to where the lining had to go and what line thickness & spacing were to be applied. As we agreed, he used a little artistic license to get the lines flowing in the right directions around the fixed components and the result, as I'm sure you will agree was very successful.

And as for the wheels:

As you will recall, these were left unpolished by the platers, so that they were plated directly onto blasted steel. The edges of the rims were masked off and the centres etch primed, and had to be filled & rubbed back smooth - the blasted surface was a little rougher than expected. Then followed the two-pack Damask Red gold lining and several coats of lacquer.

Here is a shot of John Spurgeon in his workshop, an area he uses for preparation, spraying base colours & lacquer:

And here is the other half of their shop. This area is used for finer finishing artwork, lining etc:

I'll be back there again for painting on my next project.

And here it is, back on the bike. It's not as pink as it looks in this shot:

A bit more fetching than the last time I took a 'whole bike' picture:

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!

Back in the bike

And so, bottom end set up, we can put it back in the bike.

No pics I'm afraid - just this one. That's me trying to figure out why the last engine bolt won't go in.

Hot tip - fit the rear ones before you fit any of the front ones! and make sure the oil pipes are hooked up to their stud before you fit the engine bolts!

End Float

So now we have the crankshafts, rods and cases assembled:


Ain't she pretty?

Next stop, setting end float. Not a difficult job, but you'll need a supply of shims and the right kit to measure the end float.

The Square Four is designed such that the timing side bushes form the datum against which the end float is measured. Many current machines are also built such that the timing side bush is responsible for taking any end load (there shouldn't be much) from the crankshafts into the cases, since most folk fit main roller bearings without the original lip.

The load is taken into the bronze face shown here. This is the rear crankshaft:

The front one is similar:

Excuse the picture quality. Blackberry camera - 'nuff said.

There is a large, thick washer fitted of the end of the crank to take the thrust into the bush:

The shims shown in this picture fit between the large washer and the end of the crankshaft, and hence the gap between the crankshaft and the face of the timing side bush. This is the 'end float' and should be in the limits 0.002" - 0.004". Draganfly stock the shims.

This is how you set up to measure it:

Here, the dial test indicator is set up on a magnetic base fixed to one of the engine plates, which I have temporarily fitted to the crankcase for the purpose. You can move the crankshaft by hand, to & fro, and the DTI will show you how much it moved. You add shims until you have the movement to spec. If it doesn't move... you probably have the bush nipped up between the crank and the washer. Add all your shims! Take them away until you have the right clearance.

Preparing the Crankcases

This, as all you classic motorcycle fans will know, is a sump plate. It is extremely nasty - it is pitted, bent, and is about as flat as the surface of the moon.

I'm afraid it has to go in the bin, to be replaced by one of Drag's excellent new ones complete with drain plug and magnet. Theirs are flat, thicker and made of nice strong modern aluminium!

 

Here it is in place, trial fitted with the pick up pipe and the suction strainer. To the right of the timing side main bearing, you can see the riveted cover over the drain from the oil pressure relief valve.

 

You can also see in that picture that the oil pick up pipe bolt has been wire locked into place.

 

And unfortunately, that is where the picture record ends. My camera packed up, and now I have no record of actually assembling the cranks into the cases...

 

Until we get to here, which is just to record that I did close up those tab washers correctly! That's plumbers pipe cladding protecting the rods, by the way.

 



Crankshaft Assembly

Clean those oil ways. If you recall, we dug out the gunge during strip down. During the rebuild, we used various sizes of bottle brush to get into each oil way and scrub them clean. You will be able to see the ends of these brushes by looking into the appropriate oilway.

 



 

Before you attempt to clean the oil ways in the crankshaft, make sure you understand the lubrication system. Mr. Waller, as you would hope, has a good illustration in his book:

4G Lubrication System



The picture he shows is from the iron-engine 4G, but it is similar for the Mk1 & Mk2, with the following exceptions:

• the Mk2 uses a gear pump, not the piston pump shown
• the Mk1 & Mk2 take their rocker feed from near the rear crankshaft, from the pump return to the tank
• the oil pressure relief valve in the Mk1 & Mk2 is in the end of the front crank. There is a drilling from the outboard side of the timing side bush into the crankcase, protected by a small sheet metal cover (shown here) on the inside which is riveted to the crankcase.

You can identify each of these oil ways in the crankshafts as a separate drilling, and clean them individually. Note that the long drilling between the crankpins, the one that passes through the central flywheel, is drilled from both ends and is not straight in practice.

Use some new plugs for the oil galleries. Punch and Loctite them in place.

Next stop, connecting rods. As you will have recorded, when you stripped the engine, the 'O' mark on each rod faces the front. We are using new nuts, torqued to Ariel's specification and provided by AOMCC hero Brenton Roy.

Go and have a beer. When you have finished both crankshafts, you will have earned it!