G2 lubrication query

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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G2 lubrication query

Postby Richard Hyatt » Thu Feb 28, 2019 7:14 pm

Hi all,
We have just started our G2 after much fiddling!
The question is about lubrication,
I can see oil returning from the little hole inside the tank , and the small amount of smoking cleared from the exhaust, so clearly scavenging.
We removed the rocker inspection cover and saw a little bits of spray coming up from below , but should I see any oil oozing from the little jets above each rocker? The oil screw is fully in and back out 1/2 turn. Just nice to know what's getting to the top end.
Thank you

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Re: G2 lubrication query

Postby cbranni » Thu Feb 28, 2019 7:56 pm

Yes you should see a flow of oil from the two ports.

Colin
only dead fish go with the flow

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Re: G2 lubrication query

Postby Richard Hyatt » Thu Feb 28, 2019 8:30 pm

Hmmm,
I'll try opening up the screw .
Does that control the flow to those jets please?

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Re: G2 lubrication query

Postby cbranni » Thu Feb 28, 2019 9:13 pm

No, the screw only controls the oil flow to the inlet valve stem, if there is no oil flowing out of those two ports then there is no oil getting to the head which will cause problems.

How long has the engine run for? has the engine run long enough for the oil to get up to the head?

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Re: G2 lubrication query

Postby Richard Hyatt » Thu Feb 28, 2019 9:31 pm

It was running maybe 5 or 10 minutes at idle , no longer.
Does the oil get there on the delivery side of the pump, if delivery , then it's on the pressure side of the pump, so shouldn't take long to get there.
At the moment there's only 10-40 Initial assembly oil in the tank , soon to be changed for 40 or 50 grade.
The amount of oil being scavenged didn't seem a massive flow but it was certainly returning to the tank.
I'm used to triumphs and bsa with a powerful scavenge and the rocker supply comes from that circuit.

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Re: G2 lubrication query

Postby Ozmadman » Thu Feb 28, 2019 11:36 pm

Here's my video from a similar question on the G5 thread https://www.youtube.com/watch?v=qA5y66wfo5U showing the oil feed to the rockers and return to the tank. The oil return isn't great on these and depending how bad yours is then you could try changing the oil pump pin but this requires emptying the internal oil tank and removing it to get to the pin
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: G2 lubrication query

Postby Richard Hyatt » Fri Mar 01, 2019 6:39 am

Thank you Paul,
I reckon the return rate - glug rate!! - looked pretty similar to mine at the same engine speed as your video.
But we had no oil coming from those jets above the rockers after 5 minutes.
I would have expected it by then.
Looking at various threads, it could be any of the 3 gaskets reversed that could block it off which means a strip.
I don't want to assume that the pressure side of the pump is working fine , so I might crack the filter bolt on the nearside front to see if anything is happening there

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Re: G2 lubrication query

Postby Ozmadman » Fri Mar 01, 2019 10:00 am

The holes in the head behind the rockers are minute so try poking them out with a thin bit of wire first, mine were original blocked too!!. As for the gaskets;.. It is not possible for the base gasket or head gasket to be fitted the wrong way round as far as I am aware so the most you would have to do is take the rocker cover off and check that gasket to make sure it is fitted correctly and not covering that hole (they are usually not to accurately cut and can move slightly when fitted). If all ok there get a thin rod and push it down the hole, it should go right down to below the bottom of the barrel where it will hit the oil pump shaft. At least then you will be happy that the oil way is clear. I have a spare s/h barrel and that had a small rubber bung down that hole and I was wondering if that had been there from manufacturer (it looked purpose made) to keep the oil way clean??
Paul
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1974 Yamaha RD250B US Model 6 speed

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Re: G2 lubrication query

Postby Richard Hyatt » Fri Mar 01, 2019 12:34 pm

Many thanks Paul.
Worst case scenario is rocker box off and poke downwards.
I'll try poking the jets as well
Thank you

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Re: G2 lubrication query

Postby Richard Hyatt » Fri Mar 01, 2019 5:19 pm

hi again,
when you say the jets are minute , what are we talking size-wise please?? .015"??

just asking then I know what to look for to poke into them??

I wonder if I can remove the oil screw in the rocker box and put an air line there and blow any muck outwards rather than poke any muck inwards??

thank you

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