1961 CSR. How much oil in the sump?

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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CAB
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1961 CSR. How much oil in the sump?

Post by CAB »

Hello
How much oil should be in the sump of a 1961 G12 CSR just switching off? I'm trying to determine if my bike is wet sumping because within 24 hours following a run the bike is hard to kick over.
Thanks
CAB
Groily
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Re: 1961 CSR. How much oil in the sump?

Post by Groily »

About 8-10 fl oz (call it 1/2 a pint) is normal I think - but maybe rather easier to see whether there is a problem by looking in the oil tank. If it's full when you stop the engine, and way lower the next day, the oil has gone walkabout.
It would be quite rare I think to fill the cases enough, overnight, to make the engine harder to kick over than it would be anyway when cold.
A large sprocket on the crankshaft makes them a bit harder - as you get less turn for your kick.
TrevorCSR
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Re: 1961 CSR. How much oil in the sump?

Post by TrevorCSR »

VERY unlikely a wet sumping problem after 24 hours. I'd be looking elsewhere.
TrevorCSR
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Re: 1961 CSR. How much oil in the sump?

Post by TrevorCSR »

There should be very little oil in the sump directly after switching off. There will be some internal drain down after a while. The scavenge pump is bigger, it moves more oil than the feed pump. That's why there is air in the oil as it is returned to the tank.
CAB
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Re: 1961 CSR. How much oil in the sump?

Post by CAB »

Hello

After a couple of weeks there is 3/4 of a pint in the sump so that doesn't seem too bad after that length of time. The screws holding the cover plates on and the main pump plate retaining nuts were a little loose. I wiped off the area under the feed pump gasket but a bead of oil soon re-formed so the problem could be here. The pump seems to have been heavily modified; cover plates on the outside of each pump and lipped oil seals on the inside of the pump plate with turned down camshaft nuts and what looks like an additional oil pressure relief valve which must have been fitted by the previous owner. There doesn't seem much that can be improved there. I'm going to reassemble it with new lipped oil seals and gaskets, refill it and prime the pump, run it until the oil return becomes intermittent and then drain the sump and see how much comes out of the sump - hopefully less than 3/4 of a pump. After a bit of time to let it drain off the crankcase walls I will then leave it overnight with the pistons at TDC with a measuring jug under it and see how much comes out. If it is very little, I will leave it like this for a couple of weeks (the bike is kept at my mum's and I visit every couple of weeks or so).

The engine leaks quite a bit as well from the crank case joint but I don't what to strip it fully until I properly rebuild it with a new club crank which should hopefully be available this summer.....

Thanks

CAB
Groily
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Re: 1961 CSR. How much oil in the sump?

Post by Groily »

Sounds as if you have a Rick Gibbons type modded pump, with the oil seals etc etc. The relief valve is a big brass thing on the top, I'm guessing.
3/4 of a pint in 2 weeks wouldn't be a tragedy in my world, that's for sure. At least, I've had far worse!
So I don't think it's oil hampering the starting, as it takes a heck of a lot down there to create even the beginnings of a lock-up, plus your primary chaincase would probably be awash unless there's an oil seal on the drive side - and the clutch would probably slip as an added 'bonus', making it all too easy to kick over!
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