Crankcase oil filter question?

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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mjf65
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Crankcase oil filter question?

Post by mjf65 »

I removed the filter today and gave it a clean. It had done just less than 400 miles since being recommissoned. The filter felt looked clean with little or no debris.

Looking at the filter I understand it is filtering oil on the delivery side before it goes to the main centre bearing, is that correct? And is the relief valve there to protect the supply to the bearings if the filter gets blocked?

Thanks in anticipation.
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dave16mct
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Re: Crankcase oil filter question?

Post by dave16mct »

You should have the one piece wire mesh filter/valve/nut for 1960. The valve is a non-return valve to prevent oil from draining down from the top end. The pressure relief valve is a plunger at the other end of the filter tunnel. It's held in place by a circlip and vents into the timing case. The crankcase relief valve is in the nut on the end of the crankshaft which retains the alternator rotor and sprocket.
Dave
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1608
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Re: Crankcase oil filter question?

Post by 1608 »

Unfortunately the relief valve will only empty into the timing cover and then into the sump.It will not lube the b/end shells. On cars, you are correct if oil by-passes the filtre relief valve it will lube the b/ends.
mjf65
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Re: Crankcase oil filter question?

Post by mjf65 »

dave16mct wrote:You should have the one piece wire mesh filter/valve/nut for 1960. The valve is a non-return valve to prevent oil from draining down from the top end. The pressure relief valve is a plunger at the other end of the filter tunnel. It's held in place by a circlip and vents into the timing case. The crankcase relief valve is in the nut on the end of the crankshaft which retains the alternator rotor and sprocket.
Dave
Dave, I think someone has fitted the later felt filter on mine which must be an improvement helping to trap any smaller items of debris making there way to the central journal bearing. I'll have a look for the relief valve on my bike, will it be different as it's a magneto and dynamo version?
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dave16mct
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Re: Crankcase oil filter question?

Post by dave16mct »

So long as it's the one piece filter assembly with the felt stitched over the gauze that's good. Yes it'll be a different type of valve but it's still retaining the sprocket on your bike.
Dave.
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clive
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Re: Crankcase oil filter question?

Post by clive »

The oil pressure relief valves came and went as well as were of different type according to the year, but it is important to have the correct one according to the filter installed. The vent into the primary chaincase is along the crankshaft and relieves pressure in the crankcase as the piston descends.
clive
if it ain't broke don't fix
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