High oil pressure

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Location: Victoria AUSTRALIA

High oil pressure

Postby hdawson » Thu Jan 18, 2018 6:29 am

Hi All.
I have an issue with oil pressure.
After my last ride (months ago due to a knee replacement) when I returned home I noticed oil covering the front of the engine around the dynamo.
Now I'm back in action I have removed the Oil filter and found that there is no felt filter.
So where do I start to diagnose the cause of what seems to be high oil pressure ?
What is the part no. of the 'oil filter' so I can order one?
Finally has anyone installed an in line cartridge type oil filter like I have put on my BSA?
Thanks in advance,

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Posts: 1559
Joined: Sun Jan 01, 1995 12:00 am

Re: High oil pressure

Postby Eamonn » Thu Jan 18, 2018 6:43 am

The answer about the oil/felt filter varies according to the year of manufacturer, I'm sure a model specialist will be along soon to confirm...

For an example of a cartridge oil filter fitment see thread:

If you use the Search facility on the Forum (the small magnifying glass towards the top of the screen) and enter key words such as "felt filter" or "Cartridge filter" you'll find a number of entries that may prove useful reading.

Corners like a Lego man

Posts: 89
Joined: Wed Nov 18, 2015 7:43 am
Location: wiltshire

Re: High oil pressure

Postby g5wqian » Thu Jan 18, 2018 7:01 am

its a common thing for oil leaking at the dynamo and timing case joint . .
i had a leak on my twin and first of all the dynamo was a little loose allowing oil to get out from the timing case joint .

the problem with saying tighten the dynamo bolt up is that its only small and can easily be overtightened , so you need to be carefull and not strip the stud out of the dynamo casing .

its a simple job to remove the dynamo and replace the cork seal , i put welseal on the cork seal and after installing dynamo left it overnight to cure before running engine .

one thing i would say is that if you have spotted oil at the dynamo area then you may need to check inside the dynamo for oil as mine had oil inside , so i took it off and rebuilt it with new seal and bearings and brushes etc .

if you do put new brushes in and when you run it up and it doesnt seem to charge , i would make sure you have a BPF filament bulb in at the time so it put a good load on the dynamo , then it may come to life easier when you apply a few revs .

i dont think the brushes necessarily seat fully at first .

its easy to flash the dynamo if you want to re polarise it for any reason .

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