SQ4 - back to the road

 A couple of days ago, the Square Four came off the bench to be replaced by the FH in order for me to torque down the cylinder head at 270 miles. The Square rolled easily onto the floor as it's great weight dictates with little left to do than fill the oil  and fuel tanks. 

It had been off the road for something like 4 weeks for a service and one evening I ladled in a gallon of fuel drained from the FH tank. It wasn't until I went to start the engine that I realised the fuel was pouring out of the fuel tap. It had dried out. Choosing the easy solution I soaked it in fuel overnight to see if I could get the cork to swell up again: 

This worked a bit but not well enough. The next day found me replacing the cork with a new one and also replacing the two o-rings in the reserve plunger that I made some years ago. 

Finally getting the engine started revealed another problem - no oil pressure. I ran it for 10 to 15 seconds or so with no success and shut the engine down. I realised that I would have to bleed the feed to the Morgo oil pump. I don't believe I have drained the tank before - the last time I changed the oil I didn't wash the tank out so the oil lines from tank to engine would never have been drained since I built the engine all those years ago. 

Bleeding the pump is very easy as it has a built-in hole for the purpose:

I was pleased to find the timing chest very clean and the sprockets and chain in excellent condition with the tensioner working properly. A few minutes with a screwdriver had oil seeping from the bleed hole and the whole thing sealed up again. 

Restarting the engine found the oil pressure leap up to 50 psi immediately. There is a little niggle here however in that normally the oil pressure will rise to 75 psi on startup from cold, but we do have different oil this time. I'm using Motul 20W-50 in place of the old green tin Duckhams lookalike that I used to buy from Halfords. 

Secondly the engine is not running very cleanly, misfiring a little. There may be some investigation to do.

FH - timing cover screws

 The Huntmaster timing cover has three different screw lengths which are not at all obvious - except for the short ones - if the screw holes are full of goo. 

I have cleaned out the screw holes with a twist drill and recut the threads with a long series 1/4" BSW tap so I know that they are in good shape. However the difference between the so-called medium length screws and the long screws is only 1/8" - so it's quite easy to get them wrong.

This afternoon, worried that a mix up of screws was leading to timing case leakage, I pulled them all out. I measured the depth of each of the holes with the vernier caliper and marked the relative depths on the timing case. I took this picture:

Now I have a good record of where the screws go. As it happens they were all in the right places.

FH - engine finished

 Yesterday I spent a bit more time attempting to finish the tappet covers. After clearing the threads in both the covers, clearing out the locating pin holes and straightening one of the locating pins on the inlet I finally got them to fit. The part numbers are identical for both inlet and outlet covers, but for some reason the one I had on the inlet fits the outlet and the one I had on the outlet fits the inlet. Go figure. There's obviously something around the locating pins, and I did notice that the original centre screw is longer than the one that I made; however, they are both on and done up and finished. 

Next I moved on to the timing cover with Wellseal and grease either side of the gasket as this cover comes off fairly regularly. 

The dynamo chain area is now liberally coated with semi-fluid grease and the cover is on. Some of the screw holes are obviously not clear for their full length and now that I have new Acme stainless steel screws I will need to run a tap through some of those holes again. I've ordered a tap from Tracy Tools - they do a very long (and expensive) tap called a 'nut tap' which will do the job nicely. 

The 'nut tap' is a very long taper tap - I'll need to cut perhaps half the length off the taper, as I really need it as a plug tap.

Next step is to close up the gearbox. I'm on the railway for the rest of the day, so that will have to wait until tomorrow.

One job I haven't really finished is the head steadies. Unfortunately despite the fact that they are retained to the head with half nuts, there is still not enough room to get a nut on the timing side - the drive side has a fin missing. It's extremely fiddly in there, there is no space, and unfortunately I have realised that you have to have the rocker cover slightly high before you can get the nuts on. I'll lift the rocker cover again next time. 

FH - dynamo chain

 In 60 stolen minutes (home early from a turn on the railway) I had an opportunity to do something on the Huntmaster. My initial thought was to set up the tappets and I had a look at the tappet cover locating pins to see what was going on with the inlet side, which doesn't fit. This job was going nowhere without a bit more time so I looked for something else to do and settled upon the dynamo chain. 

I removed the dynamo driving sprocket successfully with a small puller but I couldn't remove the driven sprocket at all; however, that was enough to allow me to put the new chain on.

For the record the cork gasket behind the driving sprocket is definitely there:

The new chain looked a bit larger in width than the one that was originally fitted; I've kept the old one just in case. The new one went on without any problems followed by the driving sprocket with a new tab washer - folded up here again for the record:

I'm a bit puzzled about the driven sprocket, which is a castle nut and has a hole for a split pin in the shaft. However, the slots in the castle nut don't fall in alignment with the hole due to the width of the sprocket and since it is fitted with a tab washer per the parts list, this is obviously correct. The tap washer is bent up correctly:

I really ran out of time to put the timing cover back on, but we'll do that tomorrow.

In the meantime, there's a curious little puddle underneath the oil filter - perhaps it's loose. Another little problem to take a look at!

FH - assembling the inner timing case

 Lots of work faces now, but an interim look at the cylinder head reveals that the valves and guides are beyond use - there is a couple of millimetres of rock at the edge of the valve head, with the valve half out of the guide. 

So, while I wait for a new set of guides, valves and springs let's start on the timing gear. Fitting the pinions is straightforward once I have deburred the Woodruff keys. The timing is set to the marks:

I've cleaned the dynamo straps since you have to have the inner timing case off to fit them. I'll plate these at some stage if I'm not too busy riding the bike:

The oil pressure release valve has been through the ultrasonic bath and has a new 5/16" ball. The old one was grooved and rusty:

Next, for the record, the pump drive washer is fitted:

I've made a small spacer from gasket paper for the end of the pump. Each of the stud threads has been cleaned up and fitted with blue Loctite thread lock:

I've used the original deep nuts - I've flattened these and recut the threads, adding a chamfer:

If you read my last post, you'll know that there is supposed to be a thrust washer in the nose of the pump, under the circlip. It needs to be 14.5 mm OD x 2 mm thick.

I had a bit of 3/4" EN11 in the lathe to make a late-pattern QD hub nut spanner, so I've used a bit to make the thrust washer:

I've left the pip in it to make it easier to get out. Next, the pump drive lock washer - the inner tang fits in a groove (like a keyway only less deep) in the end of the crankshaft. The tang on the new one is much wider than the remains of the one on the old washer  - time to get the needle files out:

With that in place, we can knock the tab washer down. On the crankshaft, I have bent the washer over both the lock nut and the pump drive sleeve:

For the record, the cam drive tab washer is knocked down too:

I've also finished polishing the timing cases:

I had to clean a lot of carbon off the timed breather sleeve before it would fit, and relieve a pip on the outside. It's fitted with the thickest cork washer available (5/32") and the gasket is coated with Wellseal. I've only done the inner face for the moment as I will want to take it off again.

Test fit:

That's it for now. Next I will probably fit the dynamo drive sprocket and it's seal, but then to do any more in here I need the dynamo and the Automatic Timing Device. Both of these bits need rebuilding.

FH Dry Build - Timing Cases

 Assembling the timing side, for the purposes of this dry build is a simple matter of cleaning the cases and clearing the threads.

There's some damage to the inner timing cover around the ATD, which I have asked the FaceBook panel of experts about:

The inner goes in place once I have cleaned the locating dowels of surface rust.

With clean thread and clean clearance holes, the outer goes on easily:

Charlie's Shed - Ignition timing, and nearby jobs

Having fitted the new carburetter to the W/NG, I thought I would look over the ignition system before I shake it down any further. I was having trouble with the idle settings and I wanted to ensure the other maintenance settings were spot-on before I investigate the idle issue.

So this morning we are looking at ignition timing and some associated jobs. Our focus here is of course my 1942 Ariel W/NG, but the points are valid for any M01 magneto equipped bike - that's all the BSA pre-unit singles, Norton singles, Triumph singles & Royal Enfield singles.

Assemble tools

Get your tool kit ready. I always use the tools I have on the bike for jobs like this - next time you do it you might be grovelling about in the gutter, so it pays to make sure you have the right tools and that they fit the relevant fasteners.

For example, I once found my magneto spanner did not fit the points hexagon properly and needed to be opened slightly - I would not have been happy if I had discovered that out in the countryside, however sunny it was that day.

For this job, you will need a drip tray. The timing case will have some blow-by from the oil pump in it and you don't want it on the floor - you will slip in it when you are pushing the bike about, and then you'll drop the bike or yourself, or both, which will spoil your day.

Last thing is to put the bike in a high gear, so you can move the engine carefully from the rear wheel.

By the way, it is important that you do these steps in the proper sequence. Anything else is going to compromise the ignition timing and hence the quality of your spark.

Remove the spark plug

Use your tool roll plug spanner and tommy bar to remove the plug.

Have a look at the plug and deliberate over the state of your mixture, piston rings, and ignition timing. This one is verging on OK in my book - no oil, it's not burnt, but it is a little dark suggesting my mixture is a bit rich. I'll not worry too much about that since I have changed the carb and we are checking the ignition timing today.

Check the cable tension

The ignition timing is controlled by the advance lever on the left hand handlebar - at least it is on Ariel singles. Ariels use a 'tight wire advance' in that the lever is pushed away from you, pulling the advance cable to advance the ignition.

To start work checking the timing, we need to make sure this cable has a little slack in it. Look at the ferrule at the handlebar lever end and make sure it is seated properly in the lever:

The other end of the cable disappears into the magneto under this little rubber boot:

There is a cable adjuster under the boot. Have a close look at the cable ferrule again and make sure the cable is a little slack - if it's not, move the adjuster until it is:

Setting the points gap

The next step is vital - work on the ignition timing with the points gap set up wrongly is a waste of time - the timing settings will be way out. The thing is, when the points are closed, the position of the points heel or pushrod relative to the cam is dictated by the position of the fixed point: if the gap is set too wide (i.e. the fixed point is further away from the moving point) the points heel will contact the cam later than if the points were set too tight - which alters the ignition timing.

Start by removing the points cover from the end of the magneto - swing the spring clip aside, or unscrew the cover.

This reveals the points and the cam. You can see the shiny surface of the cam in these two pictures:

This is where it is useful to have the bike in gear - you can move the rear wheel to move the points. It's quite difficult to access the points from under the dynamo. This 1942 bike has the short 40W E3HM dynamo - access is even worse with the long 60W E3L. You may wish to take the dynamo off while you adjust the points.

Use your toolkit magneto spanner with it's built in 0.012" feeler gauge to test the gap - look for a light dragging fit.

Use the spanner to release the lock nut under the fixed point and adjust the fixed point. Feel free to move the point - on this magneto, it is much easier to access the points with them at the 9 o'clock position, though the points are closed at this position. You must move them back onto the cam (12 o'clock position in this case) to test the gap.

Don't forget to do up the locknut when you are finished - but note that moving the locknut usually moved the fixed point a bit. Test it all again when it's done up tight.

Checking the timing

This is what we came for.

The first step, if you don't have one, is to make a graduated stick. Mine is a Wagamama bamboo chopstick; it's a good idea to drill one end for a loop of wire or string - something to stop the stick disappearing down the plug hole.

Stick it vertically in the plug hole, and move the piston with the back wheel until the piston pushes the stick upward while you hold it vertically in the plug hole. When it is as high as it goes, make a mark on the stick aligned with some convenient geographical feature - a church tower, TV mast or even the top of an adjacent cylinder head fin.

This is 'top dead centre' or TDC, the highest point in the piston's travel. Use a ruler to measure some graduations above your mark - mark 1" in 1/4" increments, with something indelible like a Sharpie marker.

An aside that you might want to consider. There are obviously more accurate methods of measure the piston position and detecting points opening than the method I describe here. This method is simple, but not particularly accurate - it's 1920's technology not 2020 technology, but it will get you going and get you home.

Personally, I get a lot of pleasure from this low-tech approach; I also ride my bikes on roads that existed when they were built and remember, with a manual advance magneto, the lever can be moved at will - there is little point in setting your piston position to the nearest half-millimeter when the lever setting is so inaccurate.

Next, wind the piston backwards and put your thumb over the plug hole. Turn the wheel forwards until you feel the air pressure trying to blow your thumb off - this is the compression stroke, where both valves are closed. Turn the wheel back a little way to bring the piston backwards down the stroke. Watch the points move around the cam, noting roughly where the points are when they open.

The Ariel I am working on uses a magneto which turns clockwise when viewed from the points, and the engine fires at something like 11 o'clock. In this case, I position the points at 9 o'clock, because I can get to them easily and place a blue Rizla cigarette paper between the points. Holding the cigarette paper, turn the engine unto the points release the paper.

Now, if I do this with the ignition lever set to full retard, the paper is released (and the engine would fire) at TDC. If I set it to full advance, the paper would be released with the engine about 5/8" advance, which we can see from the position of the stick:

The various notes Ariel issued for the bike recommend setting the ignition fully advanced at 3/8" - 1/2" BTDC, or 'Before Top Dead Centre'. Since my lever allows the ignition to be set between 5/8" and TDC, this is OK.

Remove the timing chain cover

You did remember to put a drip tray under the bike didn't you? The timing cover encloses the magneto chain and this is lubricated by leakage from the oil pump. consequently, there is always some oil within the cover and you will want to catch it as you remove the cover screws.

Check the chain tension

The timing chain needs to be maintained at a reasonable tension as it wears, or it will be carving your timing chest to pieces. If you look closely at this picture, you can see two grooves in that threaded post where the chain has touched it in the past.

The tension is not too critical, but there are a couple of points to bear in mind. Too loose, and it will be noisy and wear the case; too tight, and your magneto bearings and possibly the armature will suffer. Worse is a misaligned chain - it's quite easy to get the two sprockets out of parallel which is going to wear the chain very quickly.

The workshop manual for the W/NG says 3/8" total movement, which feels about right.

The chain tension is adjusted by moving the magneto backwards and forwards on its mounting platform. An Ariel magneto is retained by these three inaccessible bolts, which pass up through the mounting platform into the magneto. Slacken them by whatever contortionist spannering you are capable of, and pull the magneto backwards until the tension is where you want it. Before you tighten the bolts, make sure the magneto is pushed into the back of the timing case - there is a foam seal there which prevents the oil, splashing around the timing case, from coming out.

Set the timing

If your ignition timing was not to your satisfaction, you will need to loosen the magneto chain sprocket to reset the timing. Back off the nut a few turns, leaning on the rear brake lever as you do so:

Fit your puller to the large thread on the sprocket. You will have to wind the screw fully out to get it on, but once it's fully home you can wind in the screw and the sprocket will come off it's taper.

An alternative approach which you may find easier is to remove the sprocket on the camshaft rather than the sprocket on the magneto - the effect is the same, but the camshaft will not move while you put the sprocket back on, whilst the magneto might.

Set the advance lever to full advance and using your graduated stick, move the engine into the full advance position - 1/2" BTDC on my W/NG. As before, make sure it is on the compression stroke or you will have a mysterious failure to start.

Next, put your fag paper back in the points.

Turn the points by hand in the proper direction. They should move easily - you are turning the magneto armature which is no longer connected to the chain drive from the engine. Turn them until the paper is just released and no more.

Next, go back to the other side of the bike and push the magneto sprocket back onto the taper, and do up the nut. Go back to the 'Checking the Timing' section to make sure you have it set correctly; you don't need to be too fussy as the handlebar lever allows you to adjust the timing to wherever you want it.

Next, reassemble the timing cover; put the plug back in and replace the dynamo if you removed it, and go for a test ride.