AJS Matchless Twin Oil Feed and Return Hose / Line replacement

Britstuff · Jul 6, 2023

Hi:

I am in the process of changing the old neoprene rubber oil feed and return hoses on my 1959 AJS Model 31 Deluxe twin.

Questions:

1. What do most people use?

I could go with replacement original type neoprene hose and crimped? brass end caps with no jubilee or hose clips, (which is what I have right now)? Or maybe more modern reinforced type oil line and jubilee or hose clips? I cannot get my head around why the original type fitments do not just fall off! On my bike the end of the pipes attached to the oil tank just slid right off when pulled! They also show evidence of some kind of sealant in an apparent previous owners attempt to stop them leaking, or falling off.

2. Anti wet sump valve, yes or no.

Sorry, I know this a right old can of worms, i.e every one has a different opinion. On my two Norton's I do not run wet sump valves and it does not seem to be a problem. However, my AJS does currently have one fitted. I hear rumors that without it I may end up with oil seepage into the primary chain case, (currently using ATF ford type) and cause premature clutch slip. She of course does sit for extended periods without being run.

3. Oil tank gauze filter location, feed or return?

For some reason a previous owner placed the oil tank gauze filter in the oil tank return pipe, instead of the feed pipe. Seems like a bad idea, and certainly not the way it is supposed to be according to the manual. Is there a good reason the previous owner did this, or was it just a silly mistake?

Cheers,

James

Triton Thrasher · Jul 7, 2023

If your priority is to have long-lasting reliable hoses, use petrol injection hose, with hose clamps of your favourite type.

Whoever moved a gauze screen from the feed to the return made a silly mistake.

Fitting an anti-drain valve gives you opportunities to destroy your engine.

Shelby-Right · Jul 7, 2023

You said , I could go with replacement original type neoprene hose and crimped? brass end caps with no jubilee or hose clips, (which is what I have right now)? Or maybe more modern reinforced type oil line and jubilee or hose clips? I cannot get my head around why the original type fitments do not just fall off.

If you can get original style with the crimped ends is that a crimped sleeve or is it a push lock style , that would be great , there is probably slight vac on the feed side and a "little" pressure on the return but has a open end to tank , they don't see engine oil pressure . The original replacements sound tidy to me .

Matchless · Jul 8, 2023

Britstuff said:
Hi:

I am in the process of changing the old neoprene rubber oil feed and return hoses on my 1959 AJS Model 31 Deluxe twin.

Questions:

1. What do most people use?

I could go with replacement original type neoprene hose and crimped? brass end caps with no jubilee or hose clips, (which is what I have right now)? Or maybe more modern reinforced type oil line and jubilee or hose clips? I cannot get my head around why the original type fitments do not just fall off! On my bike the end of the pipes attached to the oil tank just slid right off when pulled! They also show evidence of some kind of sealant in an apparent previous owners attempt to stop them leaking, or falling off.

2. Anti wet sump valve, yes or no.

Sorry, I know this a right old can of worms, i.e every one has a different opinion. On my two Norton's I do not run wet sump valves and it does not seem to be a problem. However, my AJS does currently have one fitted. I hear rumors that without it I may end up with oil seepage into the primary chain case, (currently using ATF ford type) and cause premature clutch slip. She of course does sit for extended periods without being run.

3. Oil tank gauze filter location, feed or return?

For some reason a previous owner placed the oil tank gauze filter in the oil tank return pipe, instead of the feed pipe. Seems like a bad idea, and certainly not the way it is supposed to be according to the manual. Is there a good reason the previous owner did this, or was it just a silly mistake?

Cheers,

James

If you want to fit a tap to the feed line get one from Kingpin Components. I fitted one to my 650CSR & it's foolproof. The bike will not start until the tap is turned on as it earths the mag.

Britstuff · Jul 14, 2023

Today I am reminded of the effectiveness of fear as a learning tool!

I ordered a tap as suggested by @Matchless. However, seeing as I would have to wait a while for it to get here from England, I decided I might as well fit some modern type oil line, so I can keep using the old girl. I also decided to put back on the previously fitted wet sump valve. I checked that it was working, (and of course fitted it in the correct direction). It had been installed since before I owned the bike, so what could go wrong?

Fired her up and noted the rate of oil return was horrible, a mere dribble at best! There was oil in the feed line, so some oil was making it past the anti wet sump valve, but apparently not enough. I removed the wet sump valve, fired her up again and hey presto all was as it should be. In fact the return flow was maybe even better than it was before I fitted the new oil lines!

So today's lesson is that I will never use a wet sump valve again! Apparently some people like them, but now I know which side of the fence I am on.

In regards the debate regarding original or modern oil line. I'm pretty sure I am going to go with the modern stuff. There is no doubt that the original type crimped sleeves look far better than hose clamps. But it is also clear that I do not have the correct crimping tool for the job. Maybe I will go back the original setup some time in the future.

Thank you all for your comments.

Kind Regards,

James

Matchless · Jul 14, 2023

As I have said before, those valves are okay in a Velocette which has a roller bearing big end & taper roller mains, but I would NEVER fit one to a plain bearing engine. Also, the Velo ones were made by Velocette, as opposed to any Tom Dick or Harry. The Kingpin taps are foolproof as I found out when trying to start my AJS with it turned off. i.e. it wouldn't.

mdt-son · Jul 16, 2023

Britstuff said:
In regards the debate regarding original or modern oil line. I'm pretty sure I am going to go with the modern stuff. There is no doubt that the original type crimped sleeves look far better than hose clamps. But it is also clear that I do not have the correct crimping tool for the job. Maybe I will go back the original setup some time in the future.

James, why don't you take your hoses, pipe fittings and your oil tank to a pipe and hose service provider? They will install ferrules in a jiffy. If you are afraid of longevity of the hose connection at the oil tank, you may create kind of a barbed connection by roughening the protruding pipe ends a litttle where ferrules are placed. As noted by Shelby-Right, pressure gradients at these connections are very small, so it's about securing the hoses from disconnecting by gravity and vibration.

- Knut

Britstuff · Jul 16, 2023

Hi Knut:

Thank you for your suggestion. Yes, that is certainly a possibility. However, for now at least, I am not sure the improvement in appearance justifies the time and effort involved. That and I am probably going to have a tap, (and its associated additional weight) hanging from the feed pipe. So I think a correctly sized fuel injection hose clamp, (or two) will provide superior hold and flexibility against gravity and vibration. I can always go back to original setup sometime in the future If I choose to do so.

Cheers,

James

AJS Matchless Twin Oil Feed and Return Hose / Line replacement

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