Oil system 1960 M20

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Cliff-1959
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Oil system 1960 M20

Post by Cliff-1959 »

Hi,
As some of you know, my poor M20 had a major engine failure recently. I am gradually getting the bits ready for a rebuild and I don't want it to happen again obviously! I am trying to make sure that the oil gets to all the parts that it needs to, but I am confused by what I am reading in the various manuals of the day. There seemed to be a lot of changes going on around 1960 when my bike was made.

Firstly, my bike has a one piece gauze oil filter with a valve at the end, the manual says to replace it with a felt filter which I have bought, but what other bits do I need? The end cap, spring, valve etc?

The other thing is the non-return valve. The manual says that in 1960 it was moved to the end of the oil tunnel that houses the filter, but all I can see at the end is a round disc with a raised circle on it. It looks like the other bits may be missing, I am wondering if this could have been part of the original problem?
Any advice is welcome and much appreciated. :beer:
Cliff
Plodding along ...
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1608
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Re: Oil system 1960 M20

Post by 1608 »

For a 1960 twin the felt covered filter comes complete with a ball bearing and spring ( non return valve-to prevent oil draining back down from the rockers). What you have described as being at the end of the tunnel is the oil pressure relief valve. This is designed to open when the oil is cold and very viscous. By pushing a piece of 1" dowel ( broom stick) into the tunnel you should see the valve open.
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Cliff-1959
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Re: Oil system 1960 M20

Post by Cliff-1959 »

1608 wrote:For a 1960 twin the felt covered filter comes complete with a ball bearing and spring ( non return valve-to prevent oil draining back down from the rockers). What you have described as being at the end of the tunnel is the oil pressure relief valve. This is designed to open when the oil is cold and very viscous. By pushing a piece of 1" dowel ( broom stick) into the tunnel you should see the valve open.
Cutting up a broom as I type ... :roll:
Many thanks for the quick reply.
Plodding along ...
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Cliff-1959
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Re: Oil system 1960 M20

Post by Cliff-1959 »

Well the wife is NOT happy about me cutting up her broom! She wants to know how I expect her to fly to work.....
Plodding along ...
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Samuel
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Re: Oil system 1960 M20

Post by Samuel »

Witch way does she go ?
Sam
leswaller
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Re: Oil system 1960 M20

Post by leswaller »

:evil: Does she work in Coven Coordinates: 52°39′N 2°08′W / 52.65°N 2.14°W / 52.65; -2.14. Coven is a village in the district of South Staffordshire
Les
Rules are for the obedience of fools and the guidance of the wise
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Cliff-1959
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Re: Oil system 1960 M20

Post by Cliff-1959 »

:D :D
Plodding along ...
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Cliff-1959
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Re: Oil system 1960 M20

Post by Cliff-1959 »

Thanks for the info, stripped the relief valve down for a clean, and it all looks OK.
I got the re-ground crankshaft and other bits back from the engineers today, so I'm now ready for the rebuild .... Stand by for lots of daft questions :D
Plodding along ...
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REW
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Re: Oil system 1960 M20

Post by REW »

May be a little early in the rebuild to ask this, but it also relates to oil changes on a twin. Once drained and filters replaced and oil tank filled, does one just start up and hope the new oil quickly fills the various spaces now air filled? Can all the air be purged before the initial start up? What do the experts do?
Ron

1951 Matchless G3L thumping round the Durham Dales.
ajsph
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Re: Oil system 1960 M20

Post by ajsph »

I place the filter in a can with oil so it´s getting soaked before I use it
Poul
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