G15 mk 2 gets to Burnham Beeches

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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Re: G15 mk 2 gets to Burnham Beeches

Postby clive » Thu Sep 17, 2020 12:39 pm

Well I bit the bullet and removed the Magneto after checking the problem was not the two pickups. Forgot to check the earth pickup. When I did, on the bench, the earth brush was stuck in the holder with oil and carbon jamming it in nicely. Cleaned it up, cleaned and regreased the bearings checked resistance and continuity and it all seemed good. It now sparks consistently when rotated by hand so I decided to replace it on the bike. Now for the questions:-

!. How on earth do you get a spanner on the nut that is the bottom fixing on the mag? its difficult on an AMC twin but I cannot find anyway of doing it with the Norton engine. No wonder it was loose when I took it off.
2. Do I really need to retime using a timing disc attached to the primary drive? I have only just got the primary side leak free! The workshop manual gives a measurement before TDC but advises against this method.

As it is sunny I think I will give one of my singles an airing whilst I wait for opinions on this. Thanks
clive
if it ain't broke don't fix

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Re: G15 mk 2 gets to Burnham Beeches

Postby g80csp11 » Thu Sep 17, 2020 1:01 pm

Clive , I can do you a extended nut that goes the full length of the magneto , it overcomes your problem and is whats its designed for
just found same on ebay , so buy one of these . problem fixed

https://www.ebay.co.uk/itm/132461218280

as far as your second problem , remove the timing cover and attach timing disc to the crank , but please remember to replace the oil pump sealing seal

https://www.ebay.co.uk/itm/06-7510-NORT ... XQBNlRhIhG

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Re: G15 mk 2 gets to Burnham Beeches

Postby Mick D » Thu Sep 17, 2020 1:03 pm

clive wrote:How on earth do you get a spanner on the nut that is the bottom fixing on the mag?


Hi

The bottom fixing for the mag on mine is a bolt screwed into the mag flange wihich then passes through the timing case and is secured from inside the case with a nut and washer.

Mag Bolt.png


Regards Mick
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Last edited by Mick D on Thu Sep 17, 2020 1:09 pm, edited 1 time in total.

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Re: G15 mk 2 gets to Burnham Beeches

Postby g80csp11 » Thu Sep 17, 2020 1:08 pm

I always fit the special sholdered bolt from the inside with a star washer and the nut on the outside ( see my previous post)

https://www.rgmnorton.co.uk/buy/magneto ... t_4578.htm

https://www.rgmnorton.co.uk/buy/5-16-in ... 0_4916.htm
Last edited by g80csp11 on Thu Sep 17, 2020 4:46 pm, edited 1 time in total.

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Re: G15 mk 2 gets to Burnham Beeches

Postby Mick D » Thu Sep 17, 2020 2:39 pm

g80csp11 wrote:I always fit the special soldered bolt from the inside with a star washer and the nut on the outside


Hi

Why's that Peter? Why use the long nut as per BSA when you will always have access from the inside of the timing chest when removing the mag as you need to be in there to remove the ATD?

Regards Mick

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Re: G15 mk 2 gets to Burnham Beeches

Postby g80csp11 » Thu Sep 17, 2020 2:45 pm

because as clive says access to the nut is so difficult without the long nut

https://andover-norton.co.uk/en/shop-dr ... er-housing

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Re: G15 mk 2 gets to Burnham Beeches

Postby clive » Thu Sep 17, 2020 10:06 pm

cannot follow this disagreement about which side to fit the nut. my bolt wont remove anyway because I thought of that option. surely whichever way it is fitted you need to get at both sides to lock it up. I managed to lock mine using a small cranked ring spanner. Not on the nut but beside it giving enough friction to lock it! I will buy a BSA long bolt for next time!

So can we move on to
Is it ok to time the Norton Atlas engine using a rod in the plug hole or must I use a timing disc?
clive
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Re: G15 mk 2 gets to Burnham Beeches

Postby Mick D » Fri Sep 18, 2020 6:33 am

clive wrote:Is it ok to time the Norton Atlas engine using a rod in the plug hole or must I use a timing disc?


Hi

The engine doesn't 'know' how it has been timed - a disc is more accurate but the traditional method carefully applied will work just as well, follow up with the normal checks on plug and exhaust condition .

Regards Mick

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Re: G15 mk 2 gets to Burnham Beeches

Postby g80csp11 » Fri Sep 18, 2020 7:46 am

Clive , you must have the timing cover off to refit the magneto so fit the timing disc to the crank on that side and set the chain tension
at the same time you can check what distance the piston is down the bore at 32 deg BTDC if you want
it is still an accurate method
i use a old spark plug with a bolt threaded and locked to accurately set TDC ( in my case 8deg BTDC and After TDC ) then setting the 360 deg timing disc on the timing side crank using a adapter fitted to a piece of rubber hose

if the reason for the question is that you don't have a timing disc , either use a protractor or print a timing disc and stick it on a piece of card

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Re: G15 mk 2 gets to Burnham Beeches

Postby G15 Roy » Fri Sep 18, 2020 7:58 am

don't forget to wedge open the auto unit.
Roy

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