Could this be the problem

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
PX207
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Re: Could this be the problem

Post by PX207 »

Evening all, just thought I'd give you an update. Unfortunately the Indian rope trick didn't work in my favour, maybe I was too cautious or was doing it wrong! Anyway decided to take the head off to get a good look-see. Whilst I'm at this stripped stage is there anything else I should do? Please take into consideration that my talent is limited but I'm very enthusiastic and want to learn.

Regards Paul
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Re: Could this be the problem

Post by SPRIDDLER »

Was the valve stuck open?

You could check for valve guide wear but probably not necessary if the zorst hasn't been producing blue (oily) smoke.
As it's the inlet valve that appeared to be stuck open it's unlikely to be due to carbon coke build-up on the stem behind the valve head (more likely on the zorst valve) but you'll need to ascertain the cause or it's likely to stick again. Maybe the inlet valve oil metering screw needs to be opened a bit more or its oil feed drilling is obstructed.

If the old copper cyl head gasket isn't damaged you can re-use it but you must anneal (soften) it first - same with a new gasket.

I'd strongly recommend that you replace the top pushrod seals with Viton 'O' rings. I think I used 3 on each pushrod on my '54 G3LS. but it'll be pretty obvious when you trial fit the cyl head. They are available from club spares dep't.
https://www.amoc-parts.com//store/comer ... duct=24102

The reason for using the Viton seals and further guidance is in this thread:

viewtopic.php?t=8963&start=10

Before you replace the rocker box check that there isn't compressed crud/debris at the bottom of the blind threaded rocker box bolt holes in the cyl head. If there's crud at the bottom (old gasket scrapings etc) of those holes the rocker cover bolts will feel tight but won't have pinched the gasket tightly enough to prevent oil leaking out of the r/box to cyl head joint. It's quite common for owners try to tighten the bolts more in an effort to stop the leak and strip the the threads in the ali cyl head.
Last edited by SPRIDDLER on Mon Jan 16, 2023 8:54 pm, edited 1 time in total.
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SPRIDDLER
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Re: Could this be the problem

Post by SPRIDDLER »

A pic may help.
I've mentioned 3 'O' rings but it may need 4 (I can't remember - I'm old) as mentioned in my post above.
You only need washers 'B' and 'C'. The steel washer 'B' is usually well stuck in the cyl head so check thoroughly.
Pushrod tube washers and seals annotated pic.jpg
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PX207
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Re: Could this be the problem

Post by PX207 »

Thanks Spriddler, I'll get some O Rings added to my order.
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Re: Could this be the problem

Post by PX207 »

Gave the piston a quick wipe.
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Re: Could this be the problem

Post by PX207 »

Afternoon all, today's update involved removing the valves for inspection. The valve springs came off relatively easy, I didn't have to use a tool, which was a bonus! Exhaust valve slipped out on it's own, but the Inlet valve was a different matter and only came out with some persuasion. Before taking it out I did notice some slight knurling to the collet/spring end of the valve but other than that the valve looks straight and was oily.

Any reasons why the Inlet valve would be so tight as I'm baffled! Both valve guides look good, to my untrained eye, with no scoring.

Silly question time but are the markings on the piston induction of standard size?
Last edited by PX207 on Tue Jan 17, 2023 3:59 pm, edited 1 time in total.
PX207
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Re: Could this be the problem

Post by PX207 »

On another note, not sure what type of sealant this is on the pushrod covers, but I don't think it should be there. A good clean before refitting with new seals me thinks :D
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clive
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Re: Could this be the problem

Post by clive »

I suspect that is red hermatite, used to be my go to sealant but it does tend to go hard, especially with some heat. It could well be it was used because the correct dished washer C above was missing.
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Re: Could this be the problem

Post by jackstringer »

Oh you have a DPO that was a Hermatitist.

Some people go a bit mad with the stuff so it's worth checking the oil ways etc. Use an airline to check some if the ones in the head.

I remember spending house scraping off lots of excess red stuff and using proper seals and gaskets to seal it up, just with the odd slither to help hold it in place.
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Re: Could this be the problem

Post by PX207 »

clive wrote: Tue Jan 17, 2023 7:10 pm I suspect that is red hermatite, used to be my go to sealant but it does tend to go hard, especially with some heat. It could well be it was used because the correct dished washer C above was missing.
That sounds like the stuff! Although the dished washer was in place, as well as the big rubber seal, which wasn't in good shape.
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