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Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Postby Biscuit » Thu Dec 27, 2007 2:15 pm

I believe Graham, that Itma has the later type cases that dispense with the hollow bolt.




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Postby Samuel » Thu Dec 27, 2007 2:18 pm

Would not some pictures clarify this puzzle ?
Sam

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Postby Biscuit » Thu Dec 27, 2007 2:45 pm

Unfortunately Samuel, there are no 'official' pictures of the later arrangement. It would require someone with a stripped engine to photograph and post.




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Postby itma » Thu Dec 27, 2007 3:43 pm

I will post some pics tonight hopefully; the cases are 1960, not sure what qualifies as later here, I am begining to wonder if this is not a friday afternoon bike... That someone has attempted to remedy.
It would explain what is a relatively low mileage bike.
I can get round the problem, I am just trying to work out what it is!!

Still wondering what happened to all that crankcase pressure, where did it go?

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Postby Locust » Thu Dec 27, 2007 4:01 pm

Alan
He only talks about one hole not two so that surely is an early case. the later ones had the two hole one breather and one bolt.

Purhaps Itma can clarify.????

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Postby Biscuit » Thu Dec 27, 2007 4:13 pm

But he doesn't have a thread in the case for the hollow bolt, or tube as they call it.

As far as I can see '59 had the single hole stator with 'Tube', whilst '61 had the two hole stator with short bolt. Can't find any reference to 1960, except the new two-hole stator was fitted to engine number 8979 and above.




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Postby itma » Thu Dec 27, 2007 7:59 pm

right then

bearing housing-one hole, thus should be early case with tube breather.
[IMG]http://i67.photobucket.com/albums/h314/moto_photos/g21.jpg[/IMG]

but entry in gearbox radius has no thread to insert tube, has no recess for the tube head to sit in.
[IMG]http://i67.photobucket.com/albums/h314/moto_photos/g23.jpg[/IMG]

therefore this must be later case?? but there is no hole for second exit in stator
[IMG]http://i67.photobucket.com/albums/h314/moto_photos/g22.jpg[/IMG]and the stator has been threaded.This buggered bolt is solid, not drilled.
[IMG]http://i67.photobucket.com/albums/h314/moto_photos/g24.jpg[/IMG]

So what has been going on here? where did all that build up of pressure find an exit? and what caused the damage to the ring lands, never seen anything like it; usually this kind of thing would have burnt down from the top.

Thanks Chris and Locust for help and offers of bits; I can sort this, but would like to know whats been going on as it bugs me.

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Postby Biscuit » Thu Dec 27, 2007 8:38 pm

Perhaps there was an interim version, no thread in the crankcase, but a hollow bolt screwing into the stator.




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Postby itma » Thu Dec 27, 2007 8:53 pm

That thought had also occured to me, but the crude cutting of the thread in the stator implies it was done by the person who cut a bsf thread over a unf one

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Postby SPRIDDLER » Thu Dec 27, 2007 9:33 pm

quote:

Still wondering what happened to all that crankcase pressure, where did it go?



In the light of no informed comment (and that I don't know a lightweight from Britney Spears) may I nervously venture to start the discussion by suggesting that I can only see 4 alternatives for the release of crankcase wind:
1) Back up past the descending piston (at the end of the power stroke and during the intake stroke). Also out of the oil control piston ring holes from inside the piston? That is of course only if these pistons have holes in the oil ring groove.
2) Past the main bearings. But you said the clutch was dry and rusty on the drive side so probably not on the drive side.
3) Back up the oil delivery or scavenge galleries/oilways/pipes.
4) Did it merely compress in the crankcase? No great pressure I imagine since the stroke is not great and I assume that the volume of the crankcase at BDC is considerably greater for example than that of say, the combustion chamber at TDC.
Could the build-up of pressure (resistance) beneath/inside the piston on the power stroke have contributed to the cracked/fractured piston skirt?
4 questions, 5 points each, and no conferring.




Edited by - SPRIDDLER on 27 Dec 2007 10:16:39 PM
I poke badgers with spoons.

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