G2 rocker oil feed updated , advice please

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
Richard Hyatt
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G2 rocker oil feed updated , advice please

Post by Richard Hyatt »

hi all,
just a delay on this topic , but thank you all for your previous thoughts - all explored - exasperation/frustration is creeping in now !!

ok - oil holes poked out all clear

rocker inspection cover off and engine running - nothing coming from the oil jets above the pushrod cups -

BUT plenty of oil splashing about generally - oil drips from rocker spindles and pushrod cups generally wet and plenty splashing about - but nothing out of the jets

rocker cover off - gasket correct oil way right way round - poke downwards about a mile down to crankshaft depth

oil squirt can nozzle into rocker cover oil entry hole and I can push oil out of the 3 little jets - 2 above pushrod cups and the 1 which squirts onto the exhaust valve area - so all 3 holes obviously clear.

there is quite obviously oil getting up there as the spindle drips oil when it's running - but not enough to come out of the jets.

I have screwed the metering screw right in and back out about 1/2 to 1 turn and I'm pretty sure that I can see oil coming out of a hole just internally and vertically above the metering screw - it squirts upwards toward the inlet rocker - should it come out of here please?? as this will bleed oil pressure off.

the return side - I have removed and cleaned the filter element - I have momentarily run the engine without the filter and chrome cap in place and loads of oil is scavenged into that filter tube - replaced the filter and plenty scavenged back into the tank little oil hole.

am I losing the head oil pressure somewhere?? if so where please - it's as if its there but disappearing before it gets out of the jets -

the rocker spindles are snug and firm with no slop or float obvious - I thought if they were sloppy it would bleed out there and not the jets

sorry for length of post - any ideas gratefully received.

I've just seen someone else's thread about the 5th head bolt ---
Re: Length of "extra" Lightweight head bolt

"Postby clanger9 » Sun Feb 04, 2018 7:05 pm

Not at all - I can certainly figure it out by measuring the depth, etc. 5/16" BSF x 3" seems "about right".

I could do with the dimensions of an original so I know how deep the bolt is supposed to go into the block. My guess is (as Paul says) that it doesn't need to be especially tight and it's just there to keep the oil feed to the head leak-free."

could that be the reason ??? as my bolt (I've just discovered) is missing
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Ozmadman
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Re: G2 rocker oil feed updated , advice please

Post by Ozmadman »

The screw in the head is to allow an oil flow to the inlet valve, if that is is undone too far then it will smoke like crazy, it just needs to be undone a bare minimal amount (about an 1/8th of a turn). All I can think of now is that the small pin that locates the oil pump shaft and allows for the reciprocating motion of the shaft is worn so that the shaft is not being allowed its full motion (not that that is much in the first place).
Last edited by Ozmadman on Sat Mar 16, 2019 9:01 am, edited 1 time in total.
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Richard Hyatt
Posts: 113
Joined: Sun Jan 27, 2019 8:52 pm
Location: Dorset

Re: G2 rocker oil feed updated , advice please

Post by Richard Hyatt »

Thank you.
I've got the top off , so side cover and oil tank off , wouldn't hurt to clean out.
I'll source a replacement pin hopefully and change over , at least I can rule that out.
Phew
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clive
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Re: G2 rocker oil feed updated , advice please

Post by clive »

First thing i recommend checking if there is no oil supply to the rockers with a heavyweight is to check the pin which locates the oil pump is in the correct way round. There is a reduction in the diameter and this should be inserted into the holder. Looking at the exploded diagram of the G2 engine it appears to be the same. Worth checking. Otherwise on the heavyweight the other cause is an airleak in the supply or a gasket inserted wrongly and covering the supply pipe. Dont know if either can apply to a lightweight.
clive
if it ain't broke don't fix
Richard Hyatt
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Re: G2 rocker oil feed updated , advice please

Post by Richard Hyatt »

Many thanks.
Just as well I possess powers of perseverance or is it stubbornness?
Richard Hyatt
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Re: G2 rocker oil feed updated , advice please

Post by Richard Hyatt »

with regard to the screwed adjuster in the head that supplies a feed to the inlet.
does this come from the pressure side?? or the return side please??
I assume the oil under pressure comes from the pump to the timing side main bearing - then into the big end etc
but also the oil under pressure goes up the barrel into the head and lubes all components there.

then gravity from the head and the cylinder wall goes down to be scavenged - into the filter and then back into the tank through the little hole visible
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clive
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Re: G2 rocker oil feed updated , advice please

Post by clive »

struggling with the lightweight design but the pump appears to function in a way similar to that on the heavyweight. In which case the oil supply to the big end will be a separate system from the supply to the rockers. The pump will supply both and so the screwed adjuster will be on the supply side. Lightweight owners will put me right if the oil does indeed go through the big end before reaching the rockers.
clive
if it ain't broke don't fix
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Duncan
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Re: G2 rocker oil feed updated , advice please

Post by Duncan »

clive wrote:struggling with the lightweight design but the pump appears to function in a way similar to that on the heavyweight. In which case the oil supply to the big end will be a separate system from the supply to the rockers. The pump will supply both and so the screwed adjuster will be on the supply side. Lightweight owners will put me right if the oil does indeed go through the big end before reaching the rockers.
Agreed that the toped feed is on the supply side on a heavyweight, the inlet oil feed is through a drilling in the head so is fed by suction/gravity/splash rather than a postive pump feed, do light weights differ?
Richard Hyatt
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Re: G2 rocker oil feed updated , advice please

Post by Richard Hyatt »

Thank you for ideas.
I'll let you know what the pin is like and if the new bolt makes any difference to the flow
Richard Hyatt
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Location: Dorset

Re: G2 rocker oil feed updated , advice please

Post by Richard Hyatt »

042044
What is the purpose of this little plunger and it's O ring please In the oil system.
I've studied diagrams of the engine , but can't work out what it does /controls?
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