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 - chasing leaks

 This is the engine to oil filter pipe on leak test. No holes there!

However, this one is the oil filter to oil tank line:

So there's a nice leak there. The next step is to rework the oil line arrangement to the filter which I will do using a slightly different route between filter and tank since I think a contributing factor to this failure has been that the oil line has exceeded its minimum bend radius.

SQ4 - a bit of maintenance and a good clean

 Now that I've finished installing the electronic ignition and the FH is doing sterling service as the daily rider, it's time for the grubby old Mk1 to get some attention. Looking at the maintenance schedule shown here, there's a few bits that need attention not least an oil & filter change with a tank washout.

My U-Pol degreaser works wonders on the back wheel:

The next step is to lift the fuel tank and clean the cylinder head.

W/NG - fixing oil leaks

 Blatting about at the weekend used a bit of oil, some of it coming from the top end.

I suspect some is coming down the exhaust guide, but some is coming from the rocker shaft end covers. 

I've only recently learnt how to tighten these properly, and I'd damaged one of the fibre washers.

It's all done properly now, with a special screwdriver I made. I've added a small dose of Threebond to the fibre washers as well. 

Leak Test

As I may have mentioned I have a leak in the fuel tank. I found a product online called 'Seal-All' which purports to be suitable for leaky tanks and is 'gasoline proof'.

I thought I would devise a little qualification test. These are the bits we will use - ignore the regulator! The plan is to make a hole in one of the tins, seal it, and then subject it to long term immersion in fuel to determine if it leaks, or if the sealant changes.

I made a suitable hole in one of the tins using an 8 mm wad punch, which should be very similar to the hole in my tank which was cut with an over long M8 bolt. The idea is that the area of adhesive exposed to the fuel will be comparable to the real hole in the tank:

I laid the adhesive over the hole and let it cure in this position for 24 hours:

After the cure, it is still soft, like a hard cheese. 

So this is the test setup. I have fuel in the top tin, covered with a polythene bag. This is sealed to the tin with a tight elastic band, but the bag is loose to allow movement of the bag to compensate for volume changes in the air above the fuel, preventing any pressure developing in the can which would change the test conditions; the bottom can is there to catch the drips coming through the sealant from the top can:

We'll leave it for a month and see what happens, investigating periodically so that we can get a reasonable idea of how long it lasts - I don't want to look for the first time at 30 days to find a leak which may have happened after 2 days! For the record, the test started on Wednesday 31st August 2016.

Here is the first inspection, 5 days in:

Still no leaks. The sealant is a little harder - maybe a 24 hour cure is not long enough?

Second inspection, two weeks in; still no leaks:

Its possibly a little harder - I'm starting to consider where this will handle any vibration?

Latest picture. 21st September, three weeks in. No change:

More than four weeks, still no change:

6th October - five weeks:

Still no change on the 12th October - that's six weeks:

October 2024 - this repair still hasn't leaked!

Loctite 577

Remember the weep at the end of the rocker shafts? I've applied Loctite 577 thread sealer here, which should fix that problem.

Once we fix that leak, we can look for others...

Commuting

When the opportunity arises, I like to use the Square Four for ordinary day to day trips, like commuting to the office. This is great fun, and usually results in some issue appearing.

I covered about 55 miles today in a trip to Norwich, to collect some new glasses. Nice B-road trip, early start, mid afternoon back. There was a bit of rain in the morning but the Ariel didn't miss abeat - well, not due to that anyway. The return trip was dry, sunny, and much warmer than the morning had been.

Regular readers will have observed that I have had the front brake and its cable off and on a few times, trying to cure it from grabbing. Since I happened to be in the vicinity of Bungay a few weeks ago I dropped in to see the chaps at Draganfly and to pick up some new brake shoe return springs. Pulling it all apart at the weekend showed that the springs were about 3 mm shorter than the old ones - all fitted, end of grabbing problem. I even adjusted the wedge up another notch on the way out today, and no hassle from the front brake all day.

Duff old brake shoe springs

Another thing that is a persistent problem is the tank knee pads. These come loose after a few tens of miles - so I need to find a way of fixing that.

Loose knee grip

Then there is the weep from the rocker boxes - or is it the cylinder head? After a run, there is always fresh oil on the back of the block, which is worse on the nearside; you can see a stain coming from the rocker boxes, and sometimes there is a drop of oil on the rocker shaft nuts.

Offside rocker nuts, complete with drip

Here's the nearside

It looks like it dribbles off the head and onto the barrel...

Now, these engines are reputed to over-oil the top end, and of course this is worse on Morgo-equipped bikes like mine

The oil tank is often wet  on the outside, with a stream emanating from the filler cap - I fancifully wonder if this comes from the offside rocker boxes, but this is so obviously worse around the cap that I can't see that... the thing is, I routed a pipe beyond the rear wheel to allow the tank to breath & nothing comes from that.

I guess the cap just leaks. I have a new tank with a good thread, so I will change that one day. 

Something that has been niggling at the back of my mind is a misfire that appears after a long run on a hot day and gets steadily worse. Excessive carburetter temperature leading to fuel vapourization? On arriving home on a warmish day (23°C - warm for Brits!) after getting a mild misfire, getting worse in town, I found that the carb around the throttle spindle was up at nearly 90°C, and the float chamber near the main jet was around 60°C. That's got to be enough to vapourize some element of the fuel - petrol boils at 95°C (203°F)...

Infra-red thermometer. This has been useful!

I plan to fix this with a tufnol thermal barrier between the carburetter and the head. I'll probably add the proper Bi-Starter knob and the air bell when I have the carb off, and maybe make the new throttle lever spring bracket.

And the other thing? the speedo has packed up again - over-lubricated I think, it just sits at zero. I guess the clutch is slipping...

At rest. Unfortunately it still looks like that in motion...

Here are some fish for tea...

Fresh Mackerel, straight from fishing rod to kitchen!

17 mile test run; fun with brakes

Lovely test run out to Bawburgh today, about 17 miles around the countryside. Bike is definitely running less hot, since after 8 miles I still had maybe 25 psi oil pressure at 30 mph, but that was dropping to 10 psi on the gauge at the end of the trip. I measured the oil temperature - 95 degrees C in the tank (about 200 F), which is much higher than I have seen after, say, a 5 mile trip.

As you can see the bike is on the sidestand - what I noticed later was that the carburettor drips fuel onto the dynamo in this position. I had left the fuel on though. 

The engine sounds happy enough; I'm not too sure about this gauge - I keep wondering how I would feel if it had never been fitted. I'm tempted to buy one of the club reproduction gauges, or to get this one calibrated.

Out on the road though, the Ariel was handling fine for the first few miles until I became aware of a juddering from the front end, which I initially put down to the road surface. On braking however I found no movement in the front brake lever, and realised the brake was seizing on. Near home, I stopped for traffic lights and saw smoke coming from the front brake (I've been here before, with the Bantam)...

Arriving back I was greeted with grease everywhere. As we all know, hot brakes cause the grease in your hubs to melt...

Stripping the brake down revealed some serious damage to the linings, and bits of lining (2-3 mm bits) all over the drum. The linings you see in the pictures are greasy, but those matt grooves in the middle are way below the wearing surface:

Greasy

Cratered Lining

Now, I don't know if this is a result of heat, or the heat is a result of this breaking down. I'll take it back to the supplier tomorrow and see what they say.

Odd, since it had been bedding in nicely and getting quite effective.