Whats this

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Whats this

Postby Chris Berry » Tue Aug 07, 2018 8:33 am

Screen Shot 2018-08-07 at 18.25.58.png
HI there still haven't solved my oil problem. I am getting a flow at the base of the head pipe and am getting good flow back to the old reservoir which indcates that the pump is OK. The only thing that I can think of is perhaps there is a restrictor or something in the line to stop all oil going to the big end and cylinder which brings me to my question. I have attached a photo of my crankcase showing a drilling above the oil pump where the barrel bolts on. Can anyone tell me what this is and how do I get it apart to check it
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Re: Whats this

Postby dave16mct » Tue Aug 07, 2018 8:49 am

It's the cylinder oil feed, used until 1955. You can extract it by screwing a 3BA (?) bolt and levering up with a tyre lever.
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Re: Whats this

Postby Chris Berry » Tue Aug 07, 2018 9:30 am

dave16mct wrote:It's the cylinder oil feed, used until 1955. You can extract it by screwing a 3BA (?) bolt and levering up with a tyre lever.
Dave.

Thanks David. Correct me if I’m wrong but this seems to beside sort of restrictive valve. Is there a ball under it if this allowed excessive oil through would it limit the amount of oil going to the head I’m asking this because even though I am getting good return flow to the oil tank my oil pump only gets oil three quarters of the way to the head. It is a 51 Matvhless engine which had a new oil pump piston fitted 4000 miles ago

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Re: Whats this

Postby SPRIDDLER » Tue Aug 07, 2018 9:46 am

Yes, there's a spring and a ball in there.

The cylinder oiling feed was discontinued from 1955. I have a 1954 cylinder which has the oiling facility but isn't functioning (deliberately) as the cylinder base gasket doesn't have the hole in it for oil to pass from the c/case feed to the cylinder. 25,000 miles in 6 years without a problem.
You can see one of the two 180 deg spaced holes at the base of the cylinder just above the 'g' in 'dislodged'.
Scored by dislodged circlip (480x319).jpg


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Re: Whats this

Postby Chris Berry » Tue Aug 07, 2018 10:14 am

Thanks Spriddler can I assume from this that it would be safe to blank this off completely to force more oil to the head. I would assume that the barrel would be splash fed for lubrication

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Re: Whats this

Postby SPRIDDLER » Tue Aug 07, 2018 10:51 am

Well, Chris, I took the view that if it was discontinued by design then it wasn't necessary (mine always leaked slightly from that point in the c/case to cylinder gasket and down the side of the c/case).
Yes, the piston/cylinder is splash fed but I have to decline giving an opinion on whether you should do the same as I have no experience of the effect of that mod vis-à-vis your generally higher ambient temperatures and the piston to bore clearance in your engine.
The bits in the rocker box aren't stressed and need only a dribble of oil which they should get regardless of an extra supply from closing off the cylinder feed hole.
That transparent section of pipe seems to be the culprit in your anxiety. If there is oil in the rocker box (I'd just have a look in there from time to time to check) and the inlet valve isn't squeaking then I wouldn't get too hung up about seeing oil moving through the pipe.
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Re: Whats this

Postby Chris Berry » Tue Aug 07, 2018 11:42 am

Perhaps I am just getting a bit paranoid about the whole issue. I've just come back from my bike club meeting and spoke with a friend who has an ariel of the same vintage and he runs 70 grade oil in his bike with no ill effects so I might try that and, as you said, just inspect the rockers occasionally to ensure there is oil there

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Re: Whats this

Postby clive » Tue Aug 07, 2018 12:45 pm

Assuming you have no oil holes in the base of the barrel as indicated by Spriddler it will do no harm to seal off this oil supply with a 3ba screw. In fact it may help stop oil leaks from the cylinder base. If you still have the holes it will still be ok to seal off the oil supply.
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Re: Whats this

Postby clanger9 » Tue Aug 07, 2018 5:19 pm

If it gives you a bit of peace, engines like the Morini 3 1/2 v-twin have no feed whatsoever to the rockers and just rely on oil mist to lube the top end.
They seem to work just fine...
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Re: Whats this

Postby Chris Berry » Sun Aug 19, 2018 7:38 am

Thanks everyone for your input on this problem. I have since pulled the head and barrel off the engine and pulled out the oil pump plunger to investigate. On investigation I found that the gasket at the end of the oil pump housing was partially blocked thus oil was being forced past the gasket back into the oil pump (effectively recirculating the oil). I made a new gasket and the problem is now solved. Once again thanks for all the assistance

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