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Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Postby itma » Wed Dec 26, 2007 2:23 pm


On this wretched G2 I am fixing, for the owner I have come across a number of things I am unable to find the answer too.
#1 Breathing.
I have searched all the forums and links but still remain baffled as to how this thing breathes,
It has a stator with but one exit; this has been held in place by a long bolt, beautifully mangled thread, which has no holes to allow escape of air, There are no drillings any where in the bearing housing, other than the one by which this bolt enters, nor does it have a thread at the end of the tunnel as shown for a bolt that should be drilled.
So how does the thing breathe? could this build up of pressure have been the cause of this piston damage?
[IMG]http://i67.photobucket.com/albums/h314/moto_photos/piston.jpg[/IMG]
I have never seen this damage before, look at the crack on the skirt.

#2 It has been running in plenty of oil, well run in by the mixture of ground up bits of alloy and piston rings, which eventually built up in a birds nest of bits blocking the oil suction from the sump, all the bits just milled around, I have even recovered bits of piston ring from inside the main bearings.
The wear on other parts, primarily shafts has to be seen to be believed, and I have found radial cracks from the crankpin holes in both the cast iron flywheels.Is this a common fault?
I have obtained a set of CSR steel ones but of course these have a bigger crankpin than the replacement I have.
#3 Also, I can find a number stamped just in front of the oil filler, but cannot find a matching one on the other half; the cases do not look as if they are a mismatch; should there be a corresponding number on both sides? I would presume it to be so normally.

Input from any source welcomed.

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Postby Biscuit » Wed Dec 26, 2007 4:06 pm

The stator with the single hole requires hollow bolt 042221, which locates the stator. Later models had two holes in the stator, one to take a short locating bolt and the other to breathe through. Don't know what type of bolt, if any, that went in the crankcase breathing outlet on the latter layout.




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Postby itma » Wed Dec 26, 2007 5:06 pm

Alan I deduced that from the exploded drawing, as far as I can make out, that set up with the hollow bolt, had the thread under the head, female thread to match in the case . The cases I have have no thread to match what is shown in the diagrams and no trace of one.
The stator is located by a butchered 3/8 bolt in a 7/16 tunnel.
So where did all that crankcase pressure blow to? no trace of oil in the primary case, bone dry in fact and clutch a block of rust.

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Postby Biscuit » Wed Dec 26, 2007 5:46 pm

Where was this bolt? did it enter from the radius that holds the gearbox, if so, is this the hole that has no tread? which leads to the question how did it screw in?.




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Postby itma » Wed Dec 26, 2007 6:02 pm

The bolt, a unf bolt about 4 ins long, beautifully crossed threaded with a bsf thread over the unf one, enters from the radius, and is screwed into the alloy stator, which has been threaded; am I right this stator should not be threaded?
Thus this bolt pulls up at the radius end of the tunnel. All the pics I can find show this tunnel has a thread under the breather tube head.I can find no trace of one here, not even botched or removed


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Postby Biscuit » Wed Dec 26, 2007 7:37 pm

The single hole stator should not be threaded. The stator you need should have two holes, one for a short securing bolt, through the main bearing housing, the other communicates with the hole that terminates at the gearbox radius. There is nothing in this latter hole when you have a two hole stator.




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Postby itma » Wed Dec 26, 2007 8:08 pm

I am also lacking this second hole for the securing bolt ;
I knew I`d regret this bike

Whats the thinking on the result of all this confined pressure?
could it have caused the damage to the piston?
where did it all go?


Edited by - itma on 26 Dec 2007 8:10:36 PM

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Postby Biscuit » Wed Dec 26, 2007 8:16 pm

Should be simple to drill another hole.




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Postby chris kelly » Wed Dec 26, 2007 8:24 pm


Ken,

I know a man who knows...I have sent you an internal post with his phone number.

"The light singles had a timed breather on the drive side mainshaft with a rotor revolving within a stator. This last was amended for 1961 together with some other detail parts." Roy Bacon.

On my AJS14 CSR you could feel the pressure on your hand , breathing out toward the rear tyre. I used to think, rightly or wrongly, that if I overfilled the two and a half pints engine oil capacity, that oil sprayed out from this hole too.

When my bike was done up for me the cases did not match so the chap either sourced another case or did something to the existing case , I can"t remember.

Release valve. 1960 Spares List

Used on all models G2 G2CS and G5 Ken , the engine drawing in this Spares List for the 250 and 350 Overhead Valve Engine is the one that I think, could be wrong, gets reproduced everywhere.

042219 Rotor , crankcase release. One.
042220 Stator, crankcase release. One
042221 Tube, locating crankcase release. One
OOO201 Washer, fibre ,crankcase release locating tube. One
017602 Key, woodruff, crankcase release. One

Release Valve 1961 Supplementary list. To be used in conjunction with Main List for models 14 14S 14 CS 8
Parts shown in this list are confined to those that are dissimilar to the 1960 Models
042219 Rotor, crankcase release One
043036, Stator, crankcase release One
017602 Key, Woodruff crankcase release One
020016 Bolt, locating crankcase release One
000011 Washer, crankcase release


Release Valve 1962 Supplementary List. To be used in conjunction with 1960 Main List...for models 14 14 S 14CS 14 CSR 8 Parts shown etc dissimilar etc

042219 Rotor, crankcase release One
043036 Stator, crankcase release One
020016 Bolt, locating stator One
000011 Washer. stator locating bolt One
017602 Key, woodruff, crankcase release One

I noticed that there is no tube indicated ie.Part 042221 indicated after the 1960 List

I don" t think I have made any errors with these numbers, such small print..hope it helps. You are always helping other people.. but as everyone knows..mine is a limited knowledge.

Best wishes, Chris.

'My cat can beat up your cat!'

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Postby Locust » Thu Dec 27, 2007 1:12 pm

Itma
If it turns out that your crankcase halves are US I have a pair of G2 cases if you require them. You should have the thread in the first part of that hole for the hollow bolt to screw into.

Graham

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