Restoring a G80 CS

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
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Restoring a G80 CS

Postby Shorty » Mon Feb 06, 2017 12:26 pm

I am restoring a 1961 G80CS and while I have had the odd Matchless in the past, never a CS. I am a Triumph guy really but always wanted a Comp Matchy so when the opportunity arose I bought one.
Its about 60% restored but I am going through things to make sure it is right.
There were a couple of things that needed attention.
The valve lifter was not working, after a bit of fiddling that is now fixed.
The clutch is so heavy I cant pull in the lever, so I:-
Made sure the lever has a 7/8 inch fulcrum, removed the primary cover and stripped the clutch. It has 5 and a 1/2 friction plates and 5 and a 1/2 metal plates, ie one plate is friction on one side only. I checked the kick start end and made sure the ball bearing was ok and in place. Which now leads me to suspect that the three clutch springs are not original and are of such strength that when they are snugged down in the pressure plate they require a massive effort to compress. So my question is, what are the correct springs and where would I buy some?
I am sure I will have other questions but I sure would like to get the clutch sorted first.
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Shorty

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Re: Restoring a G80 CS

Postby Rob Harknett » Mon Feb 06, 2017 1:11 pm

Make sure the clutch thrust rod is not sticking or seized.

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Re: Restoring a G80 CS

Postby dave16mct » Mon Feb 06, 2017 1:37 pm

Make sure the lever under the inspection cover is in line with the cable entry. Make sure the cable is oiled and correctly routed. You may have Norton springs which are heavier than Matchless ones, cheap to change.
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Re: Restoring a G80 CS

Postby clive » Mon Feb 06, 2017 2:01 pm

Club should be able to supply the springs
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Re: Restoring a G80 CS

Postby bjork » Mon Feb 06, 2017 5:49 pm

As well as all the above, just make sure the spring adjuster nuts aren't wound in too far. I say this as I'm not sure what you mean by being 'snugged down'?
I suspect that may be too obvious a mistake as you are already used to these and other old bikes, so sorry about any egg-sucking advice.
I would normally tension them so that the adjuster flange is roughly level with the top of the spring cup. Or until the clutch no longer slips when the kickstart is used against engine compression, perhaps a bit extra for a comp type too.
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Re: Restoring a G80 CS

Postby Shorty » Tue Feb 07, 2017 12:05 pm

I would like to thank you guys for your replies.
Todays action was:
Jump in the car and drive over the other side of the city and get 3 x clutch springs from Vintage and Modern Motorcycles.
Fitted new springs, quite a bit better.
I took advice of all, Rob Harknett, push rod is ok, Dave16MT,,, good point, I got the clutch arm in line with the cable access point, and after I lubed the cable the difference was remarkable. You do know your Matchys. Set the clutch as per Bjork, no slippage while kicking over.
After a few beers and reflection on the day I gotta say that startup is a lot closer than 24 hours ago.
So now, I have lubed all the cables on the bike, adjusted tappetts, set ignition timing (1/2 inch BTDC), filled the gearbox with oil, I moved on to the fuel system.
It looks like a new Monobloc has been fitted, its been lubed up with grease so I need to strip and clean tomorrow.
I will get the camera out and take some pics.
Thanks,
Shorty

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Re: Restoring a G80 CS

Postby bjorn » Tue Feb 07, 2017 12:27 pm

The ignition setting of 1/2" piston travel from TDC (12.7mm) is for the longstrokes, and is a bit too much for the comp bikes.

For the CS models, assuming you have standard compression of about 8.7:1, use 7/16" from TDC (11.1mm). This corresponds to 38° BTDC.


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Re: Restoring a G80 CS

Postby Shorty » Fri Feb 10, 2017 12:42 am

I have some erroneous brackets, pictured below, can anyone identify them?
Image

Can anyone show or tell me where the horn mounts and also the oil tank, on the left side, I am short of some spacers or bushes. An exploded view would be most helpfull.

Image

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Re: Restoring a G80 CS

Postby dave16mct » Fri Feb 10, 2017 10:28 am

The 2 brackets on the right are front engine plates (under the mag). The 2 on the left are (I think) horn brackets. I think the horn goes under the front of the seat. There's a suitable hole in the frame casting where it turns downwards.
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Re: Restoring a G80 CS

Postby Rob Harknett » Fri Feb 10, 2017 11:03 am

Did you really fill the gearbox up with oil, or put in the correct amount only?
Fitting the clutch springs as the manual states is a good starting point. The finale adjustment made by observing the plates open evenly all round, when operated. Even with new springs they may not all be the same. You may notice somewhere the plates do not separate as much, so a spring needs letting off a bit.

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