Shields Up, Mr. Scott...

In the everlasting challenge to keep heat away from my carburetter, I have added a heat shield to the previous insulating gasket.

I know from test rides that the radiated heat from the engine is as significant as the conducted heat, so I have attempted to deal with that with a stainless steel heat shield, mounted on the front float bowl screw. Petrol boils at 95 C, and we have seen temperatures in that region on the float bowl - and we have heard the fuel boiling. So, with some spare time and in 'metal working mode', here it is:

It's bent up from a piece of 0.9 mm stainless steel I had knocking about in the shop, cut to shape with snips:

This notch is to clear the starter jet on the front of the float bowl:

Here it is in position:

It's only mounted at the top, so we should expect some vibration and potentially a fatigue failure. We'll see how effective it is tomorrow.

Oh, and by the way if you are wondering why it says 'Meyer' on the side, have a look in your kitchen cupboards. It's the bottom of a stainless steel casserole. Waste not want not!

Still Shaking

The summer is coming, the days are warming up and we need to get happy with the Square Four. Regular readers will know that it's overheated the carburetter and the chain is rubbing on the lower chain guard, but I have also noticed that the steering has been a little wayward - wayward in a 'I want to turn right' sort of way.

Having fitted the carburetter insulating gasket, it is time for another run out, this time to Aylsham M&S ostensibly to buy some rum. Initially we can see that the rear brake seems to be OK, while the front still needs some bedding in. The chain is still thrashing the chainguard.

Out in the country

Aylsham M&S, stopping for fuel

After a 12 mile run down to Aylsham we stopped for rum & fuel. I was delighted to find that I could comfortably put my hand on the carburetter float bowl - no boiling fuel here today and no misfire on the whole run. The oil pressure had been at a steady 50 psig running and about 25 psig idling so I'm delighted with that, and there doesn't appear to be any leaks either.

However, getting home there is oil all over the oil tank and the toolbox, again. This is a problem that has been recurring over a few years and I have always just cleaned it off, pretending it was down to the duff thread in the old oil tank. This time however, you will recall that have replaced the oil tank for one with a good thread, so that excuse has gone.

A short investigation reveals no seal in the tank cap... Did I really never notice that in the 6 years I have had this bike? Easily fixed fortunately.

Looking at the wheel alignment again, after the bearings were replaced in the winter, seems to be a good approach to isolating the steering problem. A few minutes with a straight board reveals a wayward rear wheel and a few minutes with the bike's toolkit it is easily fixed.

While I was under there, I had another look at the chain run and the lower chainguard. Yet another bit of judicious bending and we are done. Now we need another road test!

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.