G3L magneto removal

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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cavalier90
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G3L magneto removal

Post by cavalier90 »

I have just bought a 1941 G3L ex WD and also just joined the owners club. I suspect I have a faulty magneto but need to remove it to have it thoroughly tested. The manual gives instructions on how to release the mounting plate which has all been done successfully. The next instruction is to lift it clear. However as the shaft into the magneto still protrudes into the chain case, there is no wriggle room to lift the plate. How have the rest of you managed this? Should I unscrew the magneto from the plate before trying to lift it out? Thanks in advance.
g80csp11
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Re: G3L magneto removal

Post by g80csp11 »

its all a bit tight for space with rear mounted magneto , not least risk of petrol dripping from carb
Id recommend removing the timing cover which is easy provided the engine is at TDC compression and cams are held in there is no need to re-time

I found this manual useful on my 1946 G80L

http://archives.jampot.dk/book/Workshop ... cycles.pdf
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clive
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Re: G3L magneto removal

Post by clive »

I seem to remember this is how I had to remove the magneto on my 48 Matchless G3L before I changed the engine for an AJS one. I can now get the mag off without removing the inner timing case (never managed it without retiming) and extract the dynamo without removing the entire primary side. Of course mine is a "special" so it does not matter. :rofl:
clive
if it ain't broke don't fix
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Rob Harknett
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Re: G3L magneto removal

Post by Rob Harknett »

http://archives.jampot.dk/book/Owners_m ... Manual.pdf
Why not use your WD G3L manual, step by step instructions are on page 78..
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clive
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Re: G3L magneto removal

Post by clive »

Great advice Rob except that Cavalier90 says that he has followed the instructions in the manual and still cannot manouvere the mag out. I had this problem on both a 49 G80 and a 48 ish G3L. Undoing the bolts holding the mag to the platform is pretty difficult and not really a solution when you come to put it back. I always ended up removing the timing case.
clive
if it ain't broke don't fix
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Rob Harknett
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Re: G3L magneto removal

Post by Rob Harknett »

clive wrote: Fri Jul 30, 2021 11:32 pm Great advice Rob except that Cavalier90 says that he has followed the instructions in the manual and still cannot manouvere the mag out. I had this problem on both a 49 G80 and a 48 ish G3L. Undoing the bolts holding the mag to the platform is pretty difficult and not really a solution when you come to put it back. I always ended up removing the timing case.
Thanks for pointing that out to me Clive. I have never had a Matchless with rear of barrel mag.
Could there be a small point overlooked ? The manual instructions seem to be quite detailed.
Perhaps AMC tools were thinner & narrower to get into those tight places.
I have the odd spanner I have ground thinner & ground the ears off both sides to allow more turning space.
I cannot recall for what job I did this.
I also have small hands and fingers. I do not have problems getting nuts of grab handles on, that some people find difficult to do.


Rob
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clive
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Re: G3L magneto removal

Post by clive »

The problem is the mag platform which is specific to the rear mounted mags. It sits either side of the engine plates without the spacer you get with the forward mounted mag. As a result to get the platform clear of the engine plates you have to lift it up. This is prevented by the the drive end of the mag hitting the top of the hole in the inner timing case. I see nothing in the instructions which would help. If you remove the mag retaining bolts, which is a pig with the mag in place, its very difficult to ensure the mag is correctly seated for the chain run when you try to reverse the steps. Much easier to take the inner timing case off and retime the cams if you are unlucky enough to take the exhaust cam out with the case. g80csp11 above suggests how to prevent this, wish the forum was around when I got my 49 G80 in 1979!

I guess its possible the mounting flange on earlier N1 mags was a bit thinner allowing the method described in the manual to work but not with a later replacement N1 as the clearance problem is quite slight but frustrating.
clive
if it ain't broke don't fix
cavalier90
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Re: G3L magneto removal

Post by cavalier90 »

Magneto now off. Thanks for all the ideas. I didn't have to remove any more casings although that would clearly help. I also left the magneto attached to the plate. But today I simply lifted it up and I think I twisted it a bit, but can't be sure, and it came straight off. I almost fell over in surprise. I hope it goes back. I will try to remove it again once it has been checked and repaired if necessary and post on here how I did it.
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clive
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Re: G3L magneto removal

Post by clive »

well done not something I ever managed!!!
clive
if it ain't broke don't fix
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