barrel lubrication

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
Chris Berry
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barrel lubrication

Post by Chris Berry »

The piston and barrel of my G80 have become scuffed due to (what appears to be) heat. During the clean up process I have removed the oil pump to check there is no scoring or damage that could have caused an oil failure. The old pump looks as good as new. I then proceeded to blow out the galleries with WD40 and a straw. Everything seems clear except for the drilling at the top of the crankcase. This drilling extends down into the pump housing (it appears anyway) but it is not clear. Have poked a tiny drill bit into the hole to see how far it would go. It stops after around one inch. I then put the drill into a mandrill to see if it would go further but it all appears solid. Does anyone have any ideas as to whether this is normal and, if it is not, what can I do

Regards Chris
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Rob Harknett
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Re: barrel lubrication

Post by Rob Harknett »

Did you check your manual about this? Did you remove parts from the hole? There does appear to be a pressure relief valve fitted in it. Something I have never looked into. Hopefully the reason its solid is because parts are still in the hole. Other wise you may have damaged the crank case ball seating, by trying to get a drill through it.
Ashampoo_Snap_2017.10.23_10h35m19s_001_.png
Pistons get scuffed when used. They don't stay like new for long. I think you may be worrying about something that is quite expectable. All my bikes have scuffed pistons. I think I would be a little more concerned about damage that may now have been caused in the hole.
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Last edited by Rob Harknett on Mon Oct 23, 2017 11:00 am, edited 1 time in total.
Chris Berry
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Re: barrel lubrication

Post by Chris Berry »

Rob Harknett wrote:Did you check your manual about this? Did you remove parts from the hole? There does appear to be a pressure relief valve fitted in it. Something I have never looked into. Hopefully the reason its solid is because parts are still in the hole. Other wise you may have damaged the crank case ball seating, by trying to get a drill through it.
Ashampoo_Snap_2017.10.23_10h35m19s_001_.png
I didn't pull anything out of it nor did I force the drill so I don't think Iv done any damage (hopefully). Does your manual detail how to to get the pressure relief valve out to service it)
Chris Berry
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Re: barrel lubrication

Post by Chris Berry »

Rob Harknett wrote:Did you check your manual about this? Did you remove parts from the hole? There does appear to be a pressure relief valve fitted in it. Something I have never looked into. Hopefully the reason its solid is because parts are still in the hole. Other wise you may have damaged the crank case ball seating, by trying to get a drill through it.
Ashampoo_Snap_2017.10.23_10h35m19s_001_.png
Looking at the diagram it would appear that I was probing at the top (retainer) not the ball. As the drilling still holds liquid it is still sealing luckily. I'll have to figure out a way of pressurising the drilling from underneath to lift the ball to check its operation
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Rob Harknett
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Re: barrel lubrication

Post by Rob Harknett »

I have had a single since 1956 and have never removed anything from this hole. No fault has ever led me to believe I should investigate if there is a problem there. One of those things that has never appeared to be a problem. Bit like valve seats and guides. I have never had a problem with wear of these parts. I have head plenty of problems with these parts when owners have replaced them. Bike was running fine, but must replace valve guides and seats. Job done, after a few miles bike breaks down, guides moved seats turned. If I ever need such work done on an engine I would get an expert to do it for me.
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Rob Harknett
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Re: barrel lubrication

Post by Rob Harknett »

Looking at the diagram it would appear that I was probing at the top (retainer) not the ball. As the drilling still holds liquid it is still sealing luckily. I'll have to figure out a way of pressurising the drilling from underneath to lift the ball to check its operation.
Have you had a problem to suggest it is not operating OK ?
Chris Berry
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Re: barrel lubrication

Post by Chris Berry »

Rob Harknett wrote:Looking at the diagram it would appear that I was probing at the top (retainer) not the ball. As the drilling still holds liquid it is still sealing luckily. I'll have to figure out a way of pressurising the drilling from underneath to lift the ball to check its operation.
Have you had a problem to suggest it is not operating OK ?
Thanks Rob perhaps the attached photo might explain my concern. As are you I am an advocate of 'if it's not broken don't fix it' principle, I am concerned about the lubrications system in the bike. I think the scuffing is mainly due to piston clearance and heat but, while it is apart, just eliminating any other possible causes. Base on your comments I am satisfied that this drilling and relief valve should be trouble free. I have noticed that the groove around the base of the barrel was choked up with shit and have cleaned this out so I think I can discard lubrication issues in the future but am open to any ideas you may have

Chris
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Rob Harknett
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Re: barrel lubrication

Post by Rob Harknett »

The piston does look a bit sick Chris. It is difficult to relate to other peoples opinion of something.

For WD machines. The war department produced a book stating acceptable tolerances etc. To arrive at what is and is not acceptable. This book is in " the Archives " I was also lucky enough to get some first hand comments, from an old boy that worked on WD bikes during the war. He had offered a collection of mainly WD Matchless parts for sale. New and used. I had about a 2 hour drive to go and get the parts, hopefully to strike a deal and get back home again ASAP. I found the old boy living alone in an old peoples care home apartment. A nice 1937 AJS single engine was on display in the window of his lounge. He opened a drawer and pulled out a small box of parts. Most he had labelled with name and pt. no. He took parts out one at a time talking about each part in great detail. Some used, he explained they still had a lot more life left in them before they should be considered scrap. There were also some tools he had made. I was thinking, not much here to drive 2 hours for. Then he continued getting parts from every item of furniture in his apartment. There were very many small parts. He has saved these parts for many years and did not really want to let them go. He did still keep a few. I was with him well over 2 hours. Time not wasted, as I did learn a lot from him.

Back to your piston, it does appear to have suffered from overheating. This may not had been due to a mechanical fault. Perhaps oil level was allowed to run down or the bike running retarded. So perhaps everything in your engine is OK. But needs parts replaced, damaged due to neglect.
Mick D
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Re: barrel lubrication

Post by Mick D »

Hi

You can confirm the operation of the check valve by using a disposable medical type syringe - place the nozzle into the hole and reduce the pressure by withdrawing the plunger, the reduction should be sufficient to cause the valve to function allowing the syringe plunger to be extended, if the valve is stuck it will prevent the plunger from being withdrawn more than a little way. Check sealing by trying to force air down the hole by pressing the plunger back in, you should not be able to.

Disposable syringes are very cheap online and have a multitude of uses.

Regards Mick
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Re: barrel lubrication

Post by SPRIDDLER »

Unless there is good reason (catastrophic engine damage or build-up of sludge) there is no maintenance needed nor advised. It is not just a 'relief valve' but an oil feed to the cylinder wall.
The seat can be withdrawn by screwing a 3BA bolt into it then lever it out, and then the spring and ball can be extracted.
The cylinder base gasket should have a cutaway around this area to allow the oil to pass around the circular groove at the base of the cylinder and then out of two holes in the cylinder barrel. One of the holes is shown here above the 'G' in 'dislodged'.
Scored by dislodged circlip (480x319).jpg
The barrel shown was beyond repair so I replaced it with a later one without the oil galleries (that provision for cylinder oiling was discontinued for later models than my '54 anyway) and I used a later cylinder base gasket without the cutaway. I didn't remove or block off the oil feed/spring/ball or ball seat and it has been fine for around 20,000 miles.

To me the fairly deep scratches on your piston look as though it could have been abraded by fine swarf or other metallic contaminants in the oil. Is the cylinder wall scored or damaged?

See the text for removing the oil relief/feed components at the bottom of page 10 in this excellent article on servicing and rebuilding a Heavyweight engine by Ken Bryant (the onetime much respected 'ITMA' of this site)...
http://archives.jampot.dk/technical/Spe ... hanics.pdf
Oil feed removal.JPG
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Last edited by SPRIDDLER on Mon Oct 23, 2017 1:48 pm, edited 2 times in total.
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