Ariel Owners Motorcycle Club

Hi everyone,

After the unfortunate destruction of my engine last year, I’ve finally got all the necessary bits together and started the rebuild.

The bottom end is done with shinny new con-rods supplied by Bennet Longman. Beautiful pieces, I must say!

IMD supplied 2 new liners and pistons and Drags all the other bits and gaskets I needed. I pressed the broken liners out and the new ones in, and turned the tops of the new pistons down on the lathe. I also pressed the broken guide for the cam followers out and a good one in, which I fortunately had from a spare barrel. I also had to bang and file the damaged bridge on one of the cases back into shape, but it went OK.

I was very lucky with crankshaft and the big end. There was no damage and all it needed was a light clean up. It didn’t need a regrind or anything. I also cleaned all the sludge traps and passageways for good measure, although there wasn’t much in there, which isn’t surprising after less than 1000 miles since the first rebuild. Still, there was already some small amount of particles to be found.

Now I’m waiting to get the barrel back from the shop where the new sleeves are getting bored and the lip skimmed down. And a new OPRV body is on the way from Acme Stainless which will hopefully work this time.

I shall update as I go along.

Cheers,
Gui

Very nice!

I am delighted to see it.

How are you going to test the operation of your new pressure relief valve?

Hi Paul,
I shall test it like I did the old one - with the rig you taught me to build, using a tyre valve and a hand pump.

Hi Gui,
It's good to see that you are making some progress. It is difficult to summon-up the enthusiasm to rebuild an engine that you have only just rebuilt. I've been there, too!

I bought another new OPRV, having found that the previous new one did not want to screw into the crankshaft without a fight. I tested it when the engine was assembled by turning the engine over on the kickstart with the front crank end cap removed. I could see when oil began to be released from the OPRV, whilst watching the oil pressure gauge which I had fitted to the bike.
It surprised me that it only takes about half a dozen kicks to get the oil pressure up to about 60 psi (cold.) The OPRV started to dribble at this pressure and passed more oil as I kept on kicking.

Having since run the engine and had one short ride on the bike, the oil pressure gauge registers about 80 psi from a cold start at fast tick-over. This reduces to about 60 as the engine warms up a bit. When riding at running-in speeds, the gauge shows about 50 and reduces to 30 at tick-over when hot. The engine has new bushes/bearings/shells throughout, so I expect these numbers will change when I can put some more miles on the bike.

(I'm using 20/50 oil, btw.)

Cheers,
Allan.

Hi Gui. Please check the stud, to the left of the engine number, in the top picture. It looks as though it may be pulling out, due to a stripped thread.
I hope that I am wrong.
Cheers, Chris.

Chris, good eye, but the stud is fine. What you see is just the remains of a bit of silicone sealing I had used. It’s clean now.

Allan, my OPRV opened fine at the specified pressure. The problem was, once it opened it didn’t shut down again, dumping all the oil into the sump instead of pushing it through to the big ends. Eventually nr 3 siezed…

So far (touching wood....) my OPRV seems to be operating as it should.
My concern over this thing is, having ascertained that the ball does actually seat properly in the first place, why should it arbitrarily decide not to shut-off?

They are simple things, but the biro spring held in by a skinny split pin doesn't really inspire me with confidence....

Hi everyone,

I need some help here. Hopefully Paul Jameson can pitch in, as he seems to have the most experience with this issue.

As you know, I traced my conrod failure to a faulty pressure relief valve. The valve would open, but it failed to seal again. The valve body was a new one from Draganfly.

I now received a new one from ACME, and tested it the same way, but the same problem happens. It takes some pressure, but almost immediately it lets air through and doesn’t seal again. Exactly the same on both valves, although the pressure does go higher on the Draganfly’s valve. But one can see that air comes through as soon as I pump. I would have expected for the valve to hold some pressure before air bubbles come through, and for the ball to seal as the pressure goes back down to a certain point. But it doesn’t, releasing all the air in the system. On both valves, if I blow into it with my mouth it does seal, and my strongest blow is not able to break the seal, i.e. open the valve. But no idea what pressure can be achieved by blowing…

Could I be doing something wrong with my test? It almost seems the spring is too weak. What are your thoughts?

Video and photographs attached.

Cheers
Gui

So you are saying that it doesn't reseat? Can you introduce some oil to lubricate it and try again?