FH - where are we again?

Doesn't she look great?

  A few weeks after the last catching up post I'll write another one. It might be a bit boring for some but it's very useful to have a list of where you are and what you've got left to do, especially as there are some tiny things that get forgotten very easily - for example I've put the new gearbox inspection plug on the rocker box, and now I can't find the rocker box inspection plug...

I’ll summarise where I am in order to work out what to do next:

1. Engine: the engine is basically finished. Ignition timing is done, the oil lines are connected up and I have done the circulation on the power drill and proved that the lubrication system works properly. The next step is to finish the head steadies for which unfortunately I have to lift the rocker box slightly in order to get the nuts on. Thinking about this again, I just fitted the drive side exhaust and I'm well on the way to fitting the timing side exhaust and both of these interrupt access to the head steadies...
2. Oil System: the lubrication system is working as I said but I've realised the oil tank will have to come out because one of the seat bolts is missing; and actually the oil tank isn't bolted in properly. There's also a small leak coming from the return filter.
3. Fuel system: carburettor needs gasket sealant and the air cable shortening.
4. Ignition system: HT leads need to be terminated into their caps, and the plugs need to be screwed in.
5. Gearbox: so today I have put the kickstart case back on as you will have seen in a previous post, but I seem to have lost the inspection cap. I need to fit the gear position indicator, fill the gearbox with oil and solder a nipple onto the clutch cable but then we'll be done.
6. Clutch: I'm fairly confident that the clutch is completely finished, apart from fitting the dome.
7. Chains: primary is in, tensioned but not oiled; secondary has a dummy fitted.
8. Exhausts: the timing side is fitted but the drive side is still loose. Both of the finned clamps need to have screws made up on the lathe.
9. Electrics: the electrical system is more or less working with a couple of exceptions. The instrument panel is waiting for the speedo to come back from Chronometrics, the battery is still wired negative earth while the dynamo has not been flashed to suit. The voltage regulator enclosure still contains the original RB108 components which will need a modern conversion to suit the VRLA batteries.
10. Control Cables: the throttle and front brake cables are finished; the air cable needs the nipple moving about half an inch and the clutch cable needs both nipples replacing and the inner cut to suit.
11. Wheels & tyres: these are parked until the machine is running. I might have a look at the front brake shortly, just to clear it out before I am tempted to ride the bike around the yard!

That about sums it up. Cables next?

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!

Ariel Huntmaster vs. BSA A10

The purpose of this post is to look at the engine specifications, or the state of tune, for the various Huntmaster models and see how they compare with the closest BSA A10 models. We'll figure out which A10 is equivalent to the Huntmaster.

Here are the areas under consideration and the data I've found from reviewing the books:

Compression

• 6.5:1 Golden Flash & Huntmasters 1954-1959 
• 7.25:1 Optional for Huntmasters 1954-1959, standard for Cyclones
• 8:1 Road Rocket, Optional for Cyclones
• 8.3:1 Super Rocket
• 9:1 Rocket Gold Star

Camshaft

• 334 "standard" - fitted to the Golden Flash from 1950 - 1959 & Huntmasters 1954-1959 
• 356 "sports" - Road Rocket, Super Rocket until 1959, Golden Flash from 1960 & Cyclone
• 357 "race" - Super Flash, Spitfire Scrambler and Rocket Gold Star. Also fitted to the Super Rocket from 1960.
• 358 "acceleration".

Valves

• Inlet 1.406 Huntmaster 1954 -1959, Golden Flash 1950-1957, Super Flash / Rocket 1953-1960
• Exhaust 1.375 Huntmaster 1954 -1959 Golden Flash 1950-1957
• Exhaust 1.381 Super Flash / Rocket 1953-1960

No head changes for Cyclone

Carburettors

• 76/276 (1 1/16" bore) - Rigid and plunger framed Golden Flash, also swinging arm Golden Flash & Huntmasters in 1954.
• 10TT9 (1 1/16" bore) - Super Flash and Road Rocket, also Super Rocket until 1961.
• 376 Monobloc (1 1/16" bore) - Golden Flash swinging arm frame, Huntmasters 1955 to 1959 and Spitfire Scrambler (1956 - 1959).
• 389 Monobloc (1 1/8" bore) - Golden Flash 1960 on.
• 389 Monobloc (1 5/32" bore) - Spitfire Scrambler (1960 on), Super Rocket (1962 on) and Rocket Gold Star.

No carburetter changes for Cyclone

Conclusion

So there you have it:

• A standard Huntmaster is equivalent to a BSA Golden Flash, the most basic A10
• A Cyclone is close to a BSA Road Rocket, though with a slightly lower compression ration unless it is fitted with the optional 8:1 pistons
• My bike will be equivalent to a standard specification Ariel Cyclone.

FH - Finishing the crankshaft

In our last post, we determined that the big end clearances were good. At the same time, I checked the new gudgeon pins in the small ends and found those to be good too, so with the sludge trap cleaned and assembled some time ago we can commit to closing up the big ends with the proper big end nuts. These are £3 each, and can only be used once.

We torque them up to 22 lbf.ft, or about 29 Nm using the Draper 3/8" torque wrench.

I took the chance to clean the crankshaft down again with some brake & clutch cleaner and dropped it into the drive side crankcase half which I had laid out over the hole in my bench:

Here's another view, showing the new 356 camshaft as fitted to BSA A10 Road Rockets and early Super Rockets.

Tomorrow, I'll use some Threebond 1215 to seal the crankcase halves. Meanwhile, I need to sort out the bolts to hold the cases together. I have this lovely box of studs from Acme Stainless:

This sketch, from Draganfly's 'List 15' (a very useful document) shows where the studs go:

FH - Plastiguage and the big ends

 Next step is to check the big end clearances. I've measured the journals, but I wanted to get some evidence of the clearance that I had ended up with after fitting new -0.030" shells. There isn't much detail on what the acceptable clearance is  before you must regrind, other than the data describing the sizes you regrind to and the recommendation that there should be minimal clearance after regrinding.

Waller indicates 0.003"- 0.004" for the big end shells used on 1948-1955 Square Fours (Fifth edition page 37); Phil Irving quotes 0.001-0.0015" clearance per inch of diameter (Tuning for Speed 3rd Edition), which equates to 0.00165 - 0.0025" for my 1.65" big end. Mr. Irving, otherwise known as 'Slide Rule' using those delightful pseudonyms beloved of motoring writers in the '40's, also notes that the clearance can be much larger as long as oil pressure is maintained.

So, let's introduce Plastiguage. This is a paste, extruded into rods a bit like Plasticene. You trap a bit in the bearing and squash it, so that the known Plastiguage rod diameter is squashed to take up the clearance of the bearing - you then use the card provided to determine the clearance from the width of the squashed Plastiguage. Plastiguage comes in different sizes to measure different clearance ranges.

So, you cut a length to suite the bearing like this, and then you make up the bearing. You make sure the bearing is clean first.

When you open the bearing again you can see the squashed Plastiguage and you can compare it to the card. This suggests something like 0.002 - 0.0025" clearance for the drive side. I'm happy with that.

This is the timing side, and it's about the same:

All good there then. Next job is to make sure the oil flows into the big ends. I'll inject it into the timing side oilway:

And it comes out the drive side big end!

During this process, I removed (with a little heat) one of the gudgeon pins from the new IMD 7.25:1 pistons I got from the AOMCC so I could check the fit in the connecting rod little end bearings. This proved to be perfect once I had cleared a small burr from one side of both bearings; not sure how that came to be there.

Happy days.

FH - Sump

 This is a short post about a simple thing - hardly worth it you might think, but simple things sometimes trip us up.

I'm working up to building the bottom end, cleaning the crankcases, checking the oilways, things like that. I fitted the oil pickup pipe with a sealer called Permatex No.1, on the advice of some club members - it sets solid and that can be useful in some applications:

Here it is in place. You can also see one of the extended studs I fitted - the sump I am using is considerably thicker than standard. The studs are fitted with Loctite medium strength threadlock.

And another picture from underneath:

This is where it all goes a bit pear shaped. In the next picture you can see that the pickup pipe doesn't fit through the hole in the strainer - one of them is wrong, and this illustrates one of the pitfalls of building old bikes from bits. There is a question over which one is wrong, exacerbated by the knowledge that the strainers fitted to Huntmasters are not the same as those fitted to BSA A10s.

Now, we all know that 'the Huntmaster uses a BSA A10 engine', but actually surprisingly few parts are common. You would think, given that the crank and rods are the same and the crankcase is identical in some areas (not those relating to the timing chest, which is a different shape) that a simple thing like a sump strainer would be common too - in fact, wouldn't the canny design engineer use the bit that was already available in BSA stores? Well, no. And this my friends is perhaps indicative of why our laudable, innovative motorcycle industry went to the wall.

After contacting several experts, it transpires that the sump strainer is indeed different. Given that the strainer was manufactured by SRM (famous for BSA A10 parts) I thought perhaps I had been supplied the wrong one; apparently not. Draganfly Motorcycles, who I bought it from, actually modify the SRM A10 part into a part suitable for the Huntmaster by moving the hole.

We Ariel owners would be lost without them.

It turned out that the pickup pipe was bent - easily fixed when you know what you are aiming at.

With everything now fitting together, I decided to use Permatex again to seal the strainer to the sump plate, on the basis that the original pressed metal sump plate would have been sealed to the gauze strainer somehow as they were supplied under one part number and there is only one gasket listed in the parts book:

I greased the gasket on both sides as this is a service item and I would expect to remove it periodically.

All that remains then is to fit the sump plate. It's got a magnetic trap and this is deliberately oriented away from the pickup pipe to stop the magnet affecting the performance of the ball valve.

FH - no progress except for COVID

 Well, there's not much happening at the moment. After a few fun packed days babysitting the grandchildren, I have finally caught COVID - fortunately in it's latest rather benign variant.

In other news, the missing big end bolts have arrived from Draganfly. 

With some detailed advice on some crankcase questions, I'll start building the engine when I'm back on my feet. 

FH - Engine bottom end

 While the painted parts are away, I've got the engine on the bench. Way back when, I established the state of the bores, mains and big ends and what I want to do now is to trial fit the new large bearing crank into the original cases.

A little while in the kitchen at home saw the main bearings fitted:

It's then no more than an hour's work to assemble the crankshaft and the timing gear; the good news is that the timing gear bushes already in this case are in very good condition with very little play. Shame I already bought a new set.

It was clear that the crankshaft was a bit tight. The setup with the DTI reveals no end float and the crankshaft was mildly stiff to turn, but then it does have a large plain bush at one end:

Investigation revealed that the drive side bearing wasn't fitted fully home against the crankshaft web. With that fixed, we have 0.34 mm end float:

That's about 0.013"; we want a maximum of 0.005", according to BSA Service Sheet 208 - Waller is silent on the subject. Since 0.005" is 0.13 mm, we need to shim 0.21 mm; I've bought 0.25 mm shims which should give us 0.09 mm end float, or 0.003".

More later when bits arrive.

W/NG - last bits before she goes back on the road

I mentioned in the last post that there were a couple of things I wanted to sort out before the W/NG goes back on the road. When I refitted the clutch cable I found it was mysteriously too long - strange in that apart from replacing the missing thrust bearing everything is the same as when it came apart. Investigating, I found the clutch adjuster was missing, having been replaced by this homemade one:

AOMCC member Lee Mallabone saved the day and sent me this one, with it's adjustment bolt and ball, which incidentally is peened in place:

That was an easy fix. I took the opportunity to lubricate the cables, and the ones on the SQ4, with WD40 and my favourite cable oiler:

W/NG - first start after engine rebuild

 And there she goes:

Just a few bits left - the decompressor is not adjusted correctly and the clutch adjuster is a home made one I'd like to replace. 

W/NG - Assembling the bottom end - again...

So, a bit of spare time arrives and I have the camshaft, the cam bush, a 3/4" reamer and a gasket set. Let the bottom end rebuild commence!

First, it's back to the Rothenburger to remove and replace the bush, which I can do in one heat cycle. I'm careful to avoid the new bearing. I knock the new bush into the hot cases, driving the old bush out as I do it - a simple operation when you have enough heat.

Whilst that is cooling, let's look at the camshaft. The principle reason for replacing the camshaft is because the inner journal is badly worn. I reached out to the AOMCC Facebook community and came up with this camshaft, which is actually the profile used for the sidevalve machines. You can see it has a much longer duration than the Ariel F cam normally fitted (the one on the right), but it has the same base circle diameter. This means I will get more fuel in and and exhaust out again, and make more power but I won't have to change the followers or the pushrods.

Another problem solved by the AOMCC is the knackered half time pinion, the one at the front of the picture. A member kindly sent me the one behind, which looks unused.

Coming back to the crankcase camshaft bearings which I fitted earlier. When you buy a bush it is usually undersize, and this was no exception. It needed reaming to size, whilst aligned with the bearing in the timing chest - so I used the timing chest bearing as a guide whilst reaming the crankcase end bearing. In this next picture I have the timing chest bolted in place and a 3/4" round bar passed through both bearings to demonstrate their alignment - the bar turns smoothly and freely.

This next picture shows a block of wood I use to support the crankcase whilst working on it. The cam follower pin, crankcase nose etc. fits in the hole.

Before I assembled the engine, I fitted the camshaft so that I could prove the bearings. The camshaft turned smoothly and with no wobble, so I proceeded to dismantle it all again and to assemble the crankshaft into the cases, and to bolt the cases together.

I replaced the assembled cases in the frame and assembled the engine plates. Now that I had the crankcase held securely, I refitted the oil purifier with some Loctite 243, as suggested by Chris Williams at Alpha Bearings. A lot of folks really struggle to get these out and they often come out in pieces; I have had this one out before (and cleaned it before), so it was quite easy, but I was surprised to find it had quite a bit of sludge in it. Chris's point was that they might be difficult to get out, but if they come out when the engine is running the crankcases will be scrap.

Once that was back in, I took the opportunity to use the oil can to pump some oil into the end of the crankshaft, and eventually I saw it emerge around the big end proving that the oil ways were aligned.

Now, I could fit the new half time pinion & camshaft and set the valve timing.

I had a look at the cam followers and selected the best two. The inlet one is quite worn and I should really replace it.

Before I put the timing cover in place I need to fit the magdyno. Before I did that, I cleaned up the slip ring which was a bit mucky.

Here's a new felt seal for the magneto drive:

Next, I fitted the timing gear case with it's small gasket, and added the large gasket with Threebond 1215:

I fitted the timing gear cover and rotated the engine several times to ensure the new gears were quiet and free, adding the camshaft magneto sprocket and the magneto chain, nominally tensioned at this point. I'll finalise that when the barrel is on and I can set the timing.

Since we are nearing the end of activity from this side of the bike, I'll refit the mudguard bracket to the engine plate. The original bolt fitted here looked like it had had an M8 nut forced over a BSC thread, and both were scrap. This is a new stainless 5/16" bolt & nut.

With that done, I can fit the oil tank, hook up the oil lines and fit the oil pump.

Next, I need to clean and paint the barrel, fit the barrel & piston and set the ignition timing. Then I will close up the magneto drive having set the chain tension; I'll then inspect the clutch before I finish building the head. I know that I have to make a valve guide drift and paint the head, and possibly give the valve seats some attention - I'll do that while I wait for the clutch tab washers, nut and any other components I find damaged.