G15 Cylinder Head Removal

Information relating to the Matchless G15 or AJS Model 33 750cc twin. This also includes the G15 Mk II and the G15/45
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G15 Cylinder Head Removal

Postby Mick D » Sun Jul 26, 2020 2:48 pm

Hi

Both the Haynes Norton Manual and the Norton Hybrids manual suggest that it is possible to remove the cylinder head before removing the engine from the frame - I'm struggling to do this :(

I have removed both exhaust rockers but I can't get two of the push rods to rise sufficiently to clear the barrels.

Is it actually possible to remove the head on a AMC Duplex framed bike without taking the engine out? If so any tips?

Otherwise, will the head and barrels come of together or do I need to dig out the engine hoist, (not easy :roll: :roll: ?

Re-assembly must be a nightmare - I though the Ariel FH was bad but this is going to knock that into a cocked hat - I sense it will go back in assembled

Regards Mick

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Re: G15 Cylinder Head Removal

Postby ajscomboman » Sun Jul 26, 2020 2:54 pm

I'm led to believe it is possible but many many others have struggled and said no way! The other alternative is to let the motor drop down between the plates and swing forward allowing the head to be removed. I've never attempted this myself.

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Re: G15 Cylinder Head Removal

Postby ajscomboman » Sun Jul 26, 2020 2:59 pm

Did I fail to mention with exotica there is also pain!

Sounds like you're having a bit of fun though.

I was out on the 15 this morning and what a difference from the first ride out. It ran smooth and carbs behaved once I'd upped the idle. Rear brake is crap but was getting better. Still not 100% happy with the rotor or the clutch area and will take another look but out on the open road I enjoyed it so much I went much further than intended. Got home pulled the plugs etc and everything was spot on.

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Re: G15 Cylinder Head Removal

Postby Groily » Sun Jul 26, 2020 3:09 pm

It should come Mick.
Pushrods shoved right up into the rocker space, and then the head and pushrods lifted together, and turned through all angles to get the thing out and off. Horrible though, I absolutely agree, having done it on my P11.
Not actually any easier on a Featherbed Norton either come to that, or at least that was my accursed and mucho-cursing experience with my 650SS! Head has to come out edge-on through the top rails on them . . .
Refitting is imho even worse, as the pushrods are hard to hold in any semblance of good order while manoeuvring the head back into approximate position. But they do eventually fall onto the correct cam followers and sit squarely. I got the P11 back together without taking out any rocker shafts; the 650SS I took out the exhaust ones. But I hate doing that in case a shim does the 'Oh, do please let me fall down the pushrod tunnel' thing. Even with judicious use of soft rags, the risk is never far away . . . .

And to think folk whine about the hassle of the pushrods on Beesa pre-unit twins - complete child's play for an unsighted person with one arm compared to the Notruns! I'd happily take my A10 top off 10 times rather than do the Nortons even once.

Another very good reason why I love my AJS/M twins! If the rocker shafts could be got out 'outwards' (ie without lifting ahead), I'd say they were almost the 'perfect' design, although Triumphs are 'easy' too - for those who like that sort of thing and don't mind messing with pushrod tubes and seals like on 'our' singles.

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Re: G15 Cylinder Head Removal

Postby g80csp11 » Sun Jul 26, 2020 3:38 pm

G15 rebuild.jpg


I remember that the on the later engines the stud length was shorter slightly to allow the head to be removed so the head could be tilted
certainly on P11 its possible , but still tight
The G15 frame is of course the AMC twin frame so may still be a challenge
As Rob said , im sure you can drop the engine down on frame /plate fixings to give more access but i rebuilt mine in the frame , so as the Haynes manual always says reverse the process :rofl:
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Re: G15 Cylinder Head Removal

Postby Mick D » Sun Jul 26, 2020 3:55 pm

Thanks All

I love a challenge Rob - best part of restoration ;) and yes, I'm having a lot of garage fun :beer:

As mine is a 65 I guess I may have longer studs interfering with the Haynes method :roll:

I had begun to think about removing some engine studs and letting the engine pivot down - I'll give that some more consideration in the light of your collective comments.

Regards Mick

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Re: G15 Cylinder Head Removal

Postby Peter Morris » Sun Jul 26, 2020 9:38 pm

The method of removal is listed in the Clymer manual

Peter
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Re: G15 Cylinder Head Removal

Postby Mick D » Mon Jul 27, 2020 5:37 am

Thanks Peter

I think you have clarified the issue.

My barrels do not have a clearance groove for the centre rear stud, (unless this means the fin cut aways, (which I can't get the head far enough back to coincide with)).

I'm guessing my studs may be the longer ones too.

The inlet rocker cover area has not been relieved and this is where the interference occurs.

Could you give me more details of the Clymer book please? I sense another addition to my library.

Regards Mick

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Re: G15 Cylinder Head Removal

Postby Peter Morris » Mon Jul 27, 2020 4:46 pm

Here you go Mick,

It comes up on eBay quite frequently. There's one on there now https://www.ebay.co.uk/itm/Norton-Motor ... Sw26BfC4AY
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Re: G15 Cylinder Head Removal

Postby Mick D » Tue Jul 28, 2020 5:33 am

Thanks Peter

Reprint on the way from Amazon :beer:

Regards Mick

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