1955 G9 recomissioning

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Re: 1955 G9 recomissioning

Postby MalcW » Fri Jan 18, 2019 12:38 pm

Oggers wrote:Pear-shaped? How? I don't see any failure of big ends or main bearing occurring as the oil will just bypass. Granted it would be foolish to ignore the problem of plugged up slugde traps indefinitely, but with regular oil changes and modern single grade oils the risk of such failures - even with a plugged up trap - is IMHO minimal.


Hooray, I can relax again when I go for a ride! Especially since I have an inline cartridge filter that a PO fitted. Obviously I still have to worry about the brakes, magneto, charging, funny noises, bits dropping off etc., but that's one off the list.

One small question though: I'm running classic multigrade oil. I seem to recall reading elsewhere that it's better for the twins, which have shells rather than roller bearings?

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Re: 1955 G9 recomissioning

Postby SPRIDDLER » Fri Jan 18, 2019 12:58 pm

MalcW wrote: Obviously I still have to worry about the brakes, magneto, charging, funny noises, bits dropping off etc., but that's one off the list.

It's only bikes that are ridden anywhere that need fettling ;)

I seem to recall reading elsewhere that it's better for the twins, which have shells rather than roller bearings?

You're already using multigrade which is generally reckoned to be more shells-friendly than mono, plus the benefit of an external filter.
Chill. It'll be fine. :beer:
Last edited by SPRIDDLER on Fri Jan 18, 2019 1:56 pm, edited 1 time in total.
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Re: 1955 G9 recomissioning

Postby Oggers » Fri Jan 18, 2019 1:37 pm

Malc - if you also have a cartridge filter fitted, I think the risk would be as rare as hens' teeth - providing you change out the oil. The rest is all part of the joy of owning classics - and besides which, you would be bored otherwise. Modern multigrades tend to have detergents which pull through contaminants rather than allowing them to settle in - for example - sludge traps. However, as you have an in-line filter.......

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Re: 1955 G9 recomissioning

Postby Mick D » Fri Jan 18, 2019 1:50 pm

Hi

Mains and big ends get wrecked due to lack of lubrication when the sludge traps fill to such a point that the oil way becomes blocked - there is no by pass for this condition.

It is good engineering practice to clear the sludge traps and oil ways in the crank shaft whenever it is removed.

I would not change from monograde to multigrade oil without first overhauling an engine.

Malc - If you're running the same oil, you've had no issue so far and in view of the fact you have the added protection of a cartridge filter I wouldn't worry too much.

Regards Mick

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Re: 1955 G9 recomissioning

Postby 1608 » Fri Jan 18, 2019 3:11 pm

The whole purpose of the crank sludge trap is to collect sludge and debris by centrifugal force. The s/trap plugs are there to enable the cleaning of the s/traps for a reason. I have rebuilt several engines that the traps were dangerously full and as mentioned there is no bypass facility. I have known people to have had re-ground cranks returned without the traps being cleaned properly. All I am suggesting is that a bike with an unknown history or a re-build without provenance can be risky. I visit a number of other bike forums and have read of a number of horror stories re bottom ends giving way big time for lack of checking the sludge trap. A single with roller b/ends will complain and soon rattle sufficiently to give warning of damage/failure through lack of lubrication. a twin with shells can and probably would seize etc.etc.
I would imagine a quick search on Google re this subject will be most enlightening. I say this confidently without have looked myself.

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Re: 1955 G9 recomissioning

Postby MalcW » Fri Jan 18, 2019 5:13 pm

It's an interesting discussion. Arguably, unless you have absolute proof of what's been done to a classic bike, the very first thing you should do is completely strip it to verify the condition of the engine and gearbox. The same would, I suppose, apply to classic cars. I have never done so, unless and until a bike tells me that there is a problem, be it an outright failure, or an indication that something is not as it should be. It could be, that having dismantled things as far as is necessary for that problem, I might go a bit further, just to see how things look. Personally, if everything looks and sounds OK, and is safe to use, I would rather have some fun and get some miles in while I'm still fit enough to do so.

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Re: 1955 G9 recomissioning

Postby Mick D » Fri Jan 18, 2019 5:42 pm

MalcW wrote:Arguably, unless you have absolute proof of what's been done to a classic bike, the very first thing you should do is completely strip it to verify the condition


Hi

That's my mantra :)

To illustrate:

My current restoration has potentially run for less than 100 miles since restoration over 20 years ago - the engine oil is still golden and the engine has not wet sumped :D

But:

The clutch centre nut was loose and the dynamo drive chain void was completely clean, ie. no lubricating grease :(

Dynamo Case.png


I'll continue with the 100% strip down ;) After all, how else do you get to know your bike? :D

Regards Mick
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Re: 1955 G9 recomissioning

Postby SPRIDDLER » Fri Jan 18, 2019 7:39 pm

MalcW wrote:Arguably, unless you have absolute proof of what's been done to a classic bike, the very first thing you should do is completely strip it to verify the condition of the engine and gearbox.


Mick D wrote: I'll continue with the 100% strip down ;) After all, how else do you get to know your bike? :D


For many that would be a very unwelcome chore. Old bike pleasure for me is 85% the adventuring and the riding experience and the rest from fettling - a necessary evil.
No slight intended but I suspect that many don't have the tools/facilities/experience to do it. Probably a good few have no interest whatsoever in doing mechanical stuff. I know a couple; one a leading light in the VMCC and currently President of a one marque classic bike club who for 30 years has ridden a belt drive, no clutch, veteran bike with camping gear to many distant foreign rallies without any mechanical ability and no desire to learn either. Luckily he has chums ;)

:oops: ........In the 14 years I've had my G3LS I have never once 'cleaned' it. I do recall polishing the tank with borrowed rag and polish when I was bored at a country show and other bits get wiped over clean when I'm working on them. In fact I still have 2/3rds of the tube of Autosol that I bought when I got the bike. In 50,000 miles of home and abroad touring it has only once not got me home and that was when it was smashed up by a lorry on the wrong side of the road, wrecking the forks, flattening the footpeg and shearing off the gear lever shaft.
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Re: 1955 G9 recomissioning

Postby 1608 » Fri Jan 18, 2019 10:04 pm

Hi Mick is it your FH re-build I am following on the AOMCC. if so good luck with it and please let me know if there is anything we may be able to compare notes on. I re-built my FH basket case last year.
FH being code so as not to offend AMC owners. :rofl:

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Re: 1955 G9 recomissioning

Postby Oggers » Sat Jan 19, 2019 7:19 pm

Still don't buy the sludge trap thinking. The trap is precisely that - a trap. it is not an oilway. If the trap is full, oil surely just passes over it. There is no risk of loss of lubrication - just minor increased contamination.

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