oil filter questions

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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oil filter questions

Postby John Carney » Mon Apr 05, 2021 9:52 pm

Hi, I was planning to replace the filter on my 1961 AJS 650 model 31 so ordered a replacement (014235) but the current one is a gauze cage type. Should I just clean and leave this one as it looks perfectly serviceable or should I fit the felt one somehow instead ?
When I've checked the magnetic filter under the crankcase the magnet seems very weak. Do you think the best option is to just replace the whole thing, or is this as expected ?
Also, I was planning to replace the O ring (042025) on the chaincase inspection cap but when I've taken the cap off there seems to be a rubber seal on the chaincase itself. Do you think this should be removed ?
any help would be appreciated :) Thanks.
John

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Re: oil filter questions

Postby dave16mct » Mon Apr 05, 2021 10:27 pm

That's the wrong filter for your bike. It's from an earlier twin. Clean the gauze one and keep using that. The rubber seal sounds ok. Don't put too much oil in the primary chaincase, just touching the bottom of the chain is ok. Sump plug magnet sounds ok too.
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Re: oil filter questions

Postby 1608 » Tue Apr 06, 2021 1:14 pm

I may be wrong ( I was once ) but, isn't the gauze covered with a felt sock the correct filter for that year. I know they swapped about a bit. Its felt in my 1960 G12. Doing away with the felt type later seems a retrograde step. :? :?

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Re: oil filter questions

Postby dave16mct » Tue Apr 06, 2021 1:30 pm

Yes the one-piece gauze/non-return valve (which he has) can be covered with felt. But if he fits the felt filter he's bought it will keep the pressure relief valve open which will starve the big ends of oil. On my twins I just have the un-covered gauze filter and have a spin-on remote filter in the return line.
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Re: oil filter questions

Postby John Carney » Tue Apr 06, 2021 3:37 pm

Thanks for the replies. :) much appreciated

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Re: oil filter questions

Postby 1608 » Wed Apr 07, 2021 12:16 pm

Not wishing to confuse matters but, thats all very well if one has a screw on remote filter. I know there were several changes over the years, but believe the twin of 61 ended up with a felt covered filter. The important thing to consider is the length of the filter. It must not interfere with the relief valve. And don't be under the illusion that the relief valve will direct lubrication to the big ends, the oil just empties into the timing cover and then sump. The relief valve will only prevent oil pi**ing out everywhere and prevent the collapsing of the oil filter.

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