Saturday, 29 November 2014

Another Four Miles


Well, I have had the timing cover off and the pump is solid, so I have stripped the relief valve to reseat it. Oil pressure after a four mile run today is much the same, as we await the new spring.

Still, she's running a treat and she looks lovely!

So to get my head around engineering behind the oil pressure regulator I need to confirm what size the ball seat is, i.e. the diameter of the oilway in the offside end of the front crank. The ball is 3/16", so the seat must be maybe 5/32"? I'm trying to understand what the spring rate would need to be for a given back pressure in the system.

For example, a 5/32" seat would give an area of 0.019 sq in. exposed to pressure, so a 1 lb spring would give me about 50 psi. My existing spring is not that heavy (its the original one, new one on the way) and, surprise surprise, does not achieve 50 psi on the gauge - thats assuming the valve is ever opened!




I plan to have a look and see if the regulator valve is used next time I run the engine, and I will have to find a way of calibrating the pressure gauge..

Monday, 24 November 2014

Latest trip

Well, a bit more news today, and a four mile trip around town. 

The fuel filter has gone back in the spares box to be replaced by a plain pipe and a gauze strainer in the carburettor banjo - all air locks now banished to the spares box along with the fuel filter. Apart from a very fast tickover, all seems well in the fuel department.

I've been looking at more loose ends. I had meant to look at the chain oiler screw in the primary case for a while, since the thread in the primary chain case was refusing to allow the oiler screw to pass through it. I measured it, found it was 2 BA and cleaned it out only to realise that the screw I had was just an old carburetter mixture screw and was way too short. This is what it is supposed to look like:


Thanks to Steve Clarke for this picture.

The clutch has seen some adjustment and a much better cleanup job on the splines. It's dragging a little, but a vast improvement over what I had. Changes whilst riding are noiseless - engaging first at a standstill is still noisy but much less so. By the time I had got back it seemed to have loosened up and needed adjusting again.

The electrics are all behaving themselves; the handling is also fine but as I have discovered before I need to keep an eye on the tyre pressures - 28 in the front and 24 in the rear seems to be about right, and the consensus of opinion canvassed on the splendid AOMCC forum.

I've re-torqued the head, as regular blog readers will know. Cold, the oil pressure is about 35 psi - but this dropped to about 10 psi with the engine hot, so do we think the relief valve could be due for a new spring? AOMCC wisdom suggests that the Morgo pump may have loosened off (thanks Mark) so we will have to have a look at that before the next trip. I will get a new spring for the relief valve as well. It's getting properly hot now, but the engine is quiet and I have no exhaust or oil leaks.

Looking forward to the next trip!

Sunday, 16 November 2014

Settling Down

Time for some maintenance - re torque the head. There are a few small oil leaks around the head gasket, so I pull the nuts down a little more, maybe a 1/4 turn on each - except these guys:

These guys are only hand tight. Now I know I made a better job of that when i pulled them down the first time...

So I've worked around the head and the base gasket, pulling everything down. I've also replaced the rocker cover studs, one of which was badly stripped (at the nut, not the head, fortunately!).

So I've also had to reset the tappets, and since all the plugs were out I have bent the terminals a little to improve the HT cable routing.

I've sealed the exhausts at the cylinder head with high temperature silicone sealant, so hopefully we won't have any more exhaust or oil leaks.

Next stop was the clutch, which I have readjusted.

The final job today was to take out the inline fuel filter which served only to cause air locks. You have to be careful with these - there does not seem to be much resistance to flow but really they are better suited to pressurised fuel systems.

So that's it. She starts beautifully, coming off the bi-starter after a few minutes and settles at about 25 psi oil pressure at idle, which I am very happy with.

Just running it on the stand, the clutch seems better but it will take a road test to check that out. Since there is builder-mess outside the workshop door and my back is now aching again, we will leave it for today.