oil pump - sump - breather - pump types

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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oil pump - sump - breather - pump types

Postby greenie66 » Sun Aug 04, 2013 9:39 pm

Hi everyone, i know these topics may have been covered but i could not find them, i am new to my 1961 G12 CSR after a few years on a G80CS, i am having the following problems, and maybe someone here can enlighten me, it has the usual wet sump problem but seems very quick even for a matchless, constant drip if i leave the bolt out. Also after rinding for just a few miles the primary will start to fill with oil even after i have completely drained the sump, and after the same 2 miles there will be about 3/4 of a teacup of oil already down the bottom in the sump, my questions is how much should be at the bottom just from short trip ? is this excessive ? and does it sound like a worn out pump and a bad breather or does one affect the other should any oil be breathing into the primary case ?. - also where is the breather on a 1961 ?, is the pump the same as the earlier type, or in 1961 was it the larger pump, if i buy a G9 G11 type pump of ebay will it be the same, and does anyone supply gaskets for the pumps and pump plate, im in the USA, thanks in advance for any help

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Re: oil pump - sump - breather - pump types

Postby dave16mct » Mon Aug 05, 2013 8:50 am

Are the oilpumps the right way round on the plate, i.e. return pump (largest ) on the left, delivery pump (smallest) on the right? Your pump should be similar to the G9 / G11, but may be no better than your own. The breather is on the end of the crank, its in the large nut that holds the sprocket on. The oilpump gaskets are in the gasket set or you may get them individually from the club.
David.

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Re: oil pump - sump - breather - pump types

Postby greenie66 » Sun Aug 11, 2013 12:37 am

dave16mct wrote:Are the oilpumps the right way round on the plate, i.e. return pump (largest ) on the left, delivery pump (smallest) on the right? Your pump should be similar to the G9 / G11, but may be no better than your own. The breather is on the end of the crank, its in the large nut that holds the sprocket on. The oilpump gaskets are in the gasket set or you may get them individually from the club.
David.



left as you look at the pump or left if you are sitting on the bike ?

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Re: oil pump - sump - breather - pump types

Postby clive » Sun Aug 11, 2013 9:12 am

Looking at the pump from the side of the bike, ie the larger pump body should be at the rear. (the supply pipe is the one at the front of the engine, the return pipe at the rear). If you are draining the sump completely before a run and find 3/4 of a teacup after 2 miles this is probably what is needed to allow the return pump to start working as the sump is never actually dry. This thread seems to follow another on the site recently. I had this problem and all was resolved when a piece of broken piston ring fell out of the sump during one of the sump drains whilst the engine was hot, I was getting a reasonable return to the oil tank too despite this obstruction but once it went the chaincase stopped filling.

See the lengthy discussion in this thread http://www.ajs-matchless.com/forum/viewtopic.php?f=19&t=8650
clive
if it ain't broke don't fix it

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