FH - back to the bench

 After returning to the road following the split oil line incident, the FH has now clocked up 270 miles and it's high time to retighten the cylinder head. There are a couple of issues - it's still leaking on the drive side, and it puffs a bit of smoke from that side as well. Perhaps the return oil way is leaking oil both into the cylinder and out of the joint, onto the fins. We know from this post that there is a compression problem, and the behaviour demonstrated during the compression test supports the head gasket leak theory.

Removing the tank reveal this nasty fretting damage to the rocker oil feed pipe. Given that this pipe and it's banjos are in the way when the rocker box comes off I think I might cut the pipe here and fit a bridging rubber piece so that I can remove the banjos easily with the rocker box next time.

With the rocker box off I could get the spanners back on to the head nuts. I got quite a bit of movement on the central ones so I'm quite optimistic there will be an improvement in the compression figures for the drive side cylinder. We shall see when it's back together.

Not surprisingly perhaps but I discovered that you can't do a compression test with valves that won't open and the bike on the bench, because you can't fill the cylinders and you can't get enough purchase on the kickstart to give it a proper kick.

Never mind. While I'm under the tank I thought I'd have a look at these broken grease nipples for the steering head - this is the first time that I've successfully used an easy-out for anything!

I fitted a new one from stock, but I've only got one unfortunately...

SQ4 - rocker shaft seals

 These wet black rings are the fibre washers that seal the ends of the rocker shafts. They get very hot and are subject to oil seepage from the rocker box. 

I need some new ones.

They are not a standard fibre washer - they have a large outer diameter of about 3/4 inch but the hole in the centre is for 5/16 inch - unfortunately they are out of stock at Draganfly:

So here are the bits we need. At the top of the picture there is a 20 mm punch which I have turned from bit of handlebar on the mini lathe. Below that is the special washer and the nut that fastens the rocker shaft in place; top left is the punch used to make the central hole. The new washer is to the left - it's the grey one. 

Below is the mangled original.

SQ4 - sump plate

 The sump plate looked a bit mangled when I took it out after the oil was drained.

After degreasing I cleaned it up using some clock cleaner which is an ammoniated fluid used for stripping the corrosion from brass and copper. It works very well on the gauze.

When I got it clean, I manoeuvred the washer that stiffens the hole for the oil pickup pipe out of it's wire prison. I managed to get it back into place and squeeze it tight to retain the gauze.

With that done I could think about refitting the sump plate. I destroyed the gasket completely when I removed it so I needed to make a new one. 

With a sump plate it's easy to cut a piece of gasket paper to the right shape and to mark the holes.

Punching the holes is the easiest way to make them tidy and I used the corner of the sump plate to complete the ring of gasket around the holes.

I cut the centre out with a craft knife - it will be big enough to use for something else.

When I drained the sump, there was around a cup full of oil coming out and of course the gauze was damaged. The pickup pipe was the cause of both of these problems in that it was out of position - too high and off centre. It's just a copper pipe retained with a bracket inside the crankcase so it's quite easy to bend it into the right place.

With some Threebond 1215 the sump plate is back on and the plug fitted.

FH - looking for problems

 I snatched a few minutes in the workshop today to look at the cylinder head leak and the oily exhaust on the Huntmaster. It passes a little bit of smoke from both cylinders but nothing persistent and only when pulling away. To start the investigation and to try to eliminate the valves and valve guides and further home on the problem I thought I would do a compression test. 

I started with the drive side, which is the side that is showing oil in the exhaust pipe. This revealed a figure of something like 65 psi with the cylinder dry. Perfect compression at 7.25 to 1 should be giving us something a little over 90 psi.

This didn't improve after several kicks.

The timing side shows us something like 95 psi. The exhaust on this side is dry.

I ran a bit of oil around the top of the drive side piston in an attempt to improve the sealing and to reveal either a head gasket problem or perhaps a valve problem.

This wet test brought the compression up to 75 psi - still a bit down on where we should be. The rings have only done around 145 miles but given that the timing side is working well there is obviously a problem here, and combined with the oil leak around the top of the cylinder we are looking at a head gasket leak.

Looking at the plugs I wasn't surprised to find that they were both dark and wet. The last journey the bike had made finished with a few minutes riding at very slow speed through town - on the pilot jet. We will lean this out next time.

Riding back from the railway yesterday along the main road revealed that the bike will maintain 45 miles an hour at just under a quarter throttle - so until we are properly run-in we are not going to be able to do anything other than look at the carburettor slide cut away at the very most. We can adjust the pilot air again but we won't be able to examine the mixture from the main jet.

FH - rocker box

It's pouring with rain here today so badly that I can barely take the dogs out, so I've taken a little while to come and varnish an oak window sill and fit the rocker box to the Huntmaster. 

We start with Wellseal on the rocker box gasket faces and stick the gaskets in place. Next we'll put another coat on the cylinder head gasket faces and manoeuvre the rocker box into place over the pushrods.

I'm using a small USB camera connected to my phone to have a look in some of the small spaces around the top of the engine. The camera is small enough to go down towards the pushrod tunnels so that we can verify that the bottom end of the push rods are sitting in the tappets properly.

The camera fits through the inspection hole in the top of the rocker box and through the big spaces at the front and back to allow us to see whether the push rods are engaging with the rockers properly. You can get a small screwdriver in front or rear to nudge the pushrods into place.

With a bit of fiddling, I got the rocker box down and bolted. These bolts are actually supposed to have shakeproof washers so I shall have to change them later but the gaskets are pulled down properly. I've also fitted the rocker box oil lines.

So this all went pretty well except for one thing. Whilst the rocker box is down and I've managed to adjust the exhaust rockers to a reasonable clearance, there is no way that I can get the adjusters far enough into the rockers to bring the inlet rocker clearance to specification. I'm not sure what's wrong with this, it might be worn adjusters, it might be worn pushrods...

Wish I had had the foresight to measure the pushrods before I started...

FH - various jobs

 There's lots of little jobs around the bike to be getting on with. This one is the dynamo cork gasket which I bought from eBay. It was a little big and needed 3/8" taking out of the circumference.

That's the dynamo chain in place. I had one with a split link which I think is unusual - but I think that this is the original chain. I replaced it with an endless one from Draganfly. It's very difficult to tension because whilst you can turn the dynamo to tension the chain, as soon as you do up the clamp it pulls the dynamo back into the crankcase and loosens the chain again...

These are the clamps for the head steady. I've fitted them in place with some leather shim between the clamp and the frame to protect the paint. I'll leave these here for the moment until I have made the new studs for the rock box, and then I can fit the head steadies.

I bought all the cables as universal types from Draganfly. When I unwrapped them I was pleased to find the air and throttle cables were complete with their nipples fixed in place at both ends. Whilst the throttle cable fits ok, the choke inner cable is much too long so I will have to move the nipple.

These two pictures show the routing that I have adopted for the clutch cable. I've shortened the outer to suit this routing, and when the gearbox is back together I will fit the nipple.

I've made up two gaskets for the carburettor and the heat shield. 

Perhaps inevitably, the throttle stop is missing from the twist grip. As soon as you slacken the cable these loose stops fall out and can be easily lost. I'll make one on the lathe later - perhaps two, one for the toolbox as a spare.

FH - fitting the cylinder head

 Fitting the cylinder head didn't prove to be the routine operation that I had envisaged. I started with a coat of Wellseal on the top of the block and on the top of the gasket. Prior to this I had cleaned out the threads in the block with a new tap and cleaned the threads on the head bolts with a new die. Two of the head bolts were damaged and needed replacement.

Lowering the heavy head into place was the usual faff but eventually I got a couple of the bolts dropped in on the near side. I wanted to put the corresponding bolts in on the far side next but for some reason I couldn't get them to mate with the threats in the barrel. After a lot of messing about I pulled the head off again to have a look:

It's sometimes a challenge when you buy pattern parts - in this case you can see that the bolt pattern in the gasket is wrong and the holes don't line up. I decided, rather than to use the composite gasket in the kit, that I would anneal the original gasket and reuse it. This is very straightforward - it's just a question of heating the copper to cherry red and leaving it to cool followed by a clean up with some Scotchbrite pad.

After that, and a second coat of Wellseal, the head bolts all went in easily. Neither Ariel nor the BSA service sheets indicate a recommended torque for these bolts but they do show a pattern you have to follow when tightening them up:

All that went swimmingly, as expected, and we now have the head fitted. Of course fitting the head opens up whole new set of work faces including the carburettor, the rocker box and the exhaust pipes. OK, the exhausts will have to wait until I have finished the primary case and I'm going to repair the stops on the centre stand as well since access will be better without the pipes in place.

More later.

W/NG - Dealing with leaks

 Long fast club runs tend to reveals failings in your bike, especially when 'given the beans' by other riders. You know who you are! The oil leaks that have plagued the W/NG really made themselves felt on the 87 mile run around Norfolk that the VMCC Blakeney Run entailed. It was clear that the oil was coming from the top end, but I wasn't sure if it was the decompressor, the rocker box gaskets or the cylinder head bolts.

Having spent some resealing the decompressor recently, I removed the rocker boxes to take a look revealing that the existing aluminium gaskets did not fit at all well:

 I resolved to make some new gaskets.

I made these from Flexitallic pink gasket sheet, which I think is rated to 350°C. I made the gasket a bit wider than the aluminium one, to make sure it covered the whole joint. I sealed it in place with Threebond 1215.

Preliminary testing suggests this has sorted most of the problem, but the decompressor is still weeping a bit. I'll have to add some more shims.

Mighty Morgo

Today I fitted the Morgo oil pump made by Autovalues Engineering from Bradford.

The Morgo is a gear type pump, and is very nicely manufactured, well packed and is provided with a comprehensive set of instructions. While there are several Morgo rotary pumps for other Ariels & Triumphs, the fitting kits and instructions are bespoke to the model you are fitting. Very nice quality, well thought out.

The pump comes with a fitting kit, consisting of the left hand drive nut, a set of shims, a gasket, two tab washers and two mounting bolts

This is the drive side of the pump, showing the Oldham coupling used to drive the pump from the camshaft.

And here is the drive nut for the pump. Those slots are closely toleranced to prevent rattles and wear

Here it is in place. I've got it fitted with the original studs at the moment, since I don't like the idea of wearing threads in the soft crankcase to remove a service item but in practice you have to engage the pump coupling before bolting up - it is close fitting in its slots, as it needs to be, and this makes the bolts supplied with the pump the only practical way of fitting it.

I need to prime the pump - so I will refit it with the bolts supplied with the pump.

The head is on!

So we are all set. The sun is shining, I have a day free (after cutting the grass and making the family dinner) and I have all the parts, plus a very nice text from Bruce Longman via Draganfly with explicit instructions. Max is in bed, so he will be happy for a bit:

A Chocolate Sprocker, feeling very 'Sunday Morningish'

I have some high temperature silicone gasket as recommended by Bruce. Loctite say this is suitable for operating temperatures up to 275 degrees C (sustained) with excursions to 300 C:

So as recommended by Bruce, we start by laying a band of sealant around the pushrod tunnels, on both sides of the gasket. Actually easier to lay one bead on the gasket, and one bead on the block, making sure you have the handed gaskets the right way around:

No picture, but next I placed all the head nuts in position between the cylinder block fins, under their holes, with the flanges upward. Next, manoeuvre the head under the frame tube and drop it into place over the studs, making sure the extended, rounded ends of the studs drop into the nuts. Add the sleeve nuts inside the rocker boxes, and the 5/16" CEI reduced hex nuts outside the rocker boxes. You hand screw these down finger tight.

And as Kees Knegt pointed out in a comment to an earlier post, this would have been easier without the rockers! You cannot fit the pushrods with the rockers in place either (they don't slide sideways far enough) so I may as well have left them off... although I do like to trial fit everything at least once.

Next, with your thinnest 5/16" CEI open spanner, engage all the nuts on the downward facing head studs and turn them as far as they will go without using and force. You will realise now that if you leave one undone, and tighten the others, you will crack a fin by virtue of the loose nut pushing downward onto the fin below.

Once you have all the nuts finger tight you will see the head finally come down onto the gaskets. continue going around all the nuts inside & outside the rocker boxes until they are all snugged down finger tight.

You will need a variety of spanners to achieve this. The reduced hex nuts in the middle of the head, under the inlet tract are particularly inaccessible.

So, when everything is snugged down, use Bruce's torque figures and sequence to tighten down the head.

Job done.