Another Amal issue!

Helpful information and requests for assitance and advice
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G3L1946
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Re: Another Amal issue!

Post by G3L1946 »

Hi ajscomboman,

The carb fitted, when I bought the bike, was for a sunbeam 500 (as well as others) but not a G3LS. I bought the correct carb 376/5 and replaced all as stated previously as well as giving it a very thorough clean. I noticed the 3.5 did not tally with some documentation but later found that AMC revised the slide from a 3 to a 3.5 about six months later. No mention was made of any changes, elsewhere , that were required. I’ll check the timing as suggested and then, if necessary, re visit the carburettor.

Regards,

Steve
Last edited by G3L1946 on Sun Jan 09, 2022 7:30 pm, edited 1 time in total.
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Re: Another Amal issue!

Post by SPRIDDLER »

clive wrote: Sun Jan 09, 2022 6:17 pm Not sure I agree with you Spriddler about using the decompressor on the starting stroke.
I only use the decompressor to facilitate getting the piston just over TDC then release it for the starting kick.
(Obviously if you have knackered engines with little compression it's unnecessary to use the decompressor to get the piston over TDC). ;)
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56G80S
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Re: Another Amal issue!

Post by 56G80S »

I had this problem, it was the AR unit. Rob Harknett provided advice on cleaning it:
viewtopic.php?f=18&t=25457&p=211956&hil ... rd#p211956.

Personally, I took the A/R unit off and cleaned it out, the sheer volume of rustiness was alarming.

I also had some slight fouling of the rear of the A/R onto the inner half of the mag chaincase which didn't help (I'd previously changed the mag).

Johnny B
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G3L1946
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Re: Another Amal issue!

Post by G3L1946 »

Hi Johnny B,
Thanks for advice. I’m still struggling to get the blooming thing off! A right fiddle, bolt loosened which then goes tight. Still unable extract unit. Appears to be a common oddity!
Steve
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Re: Another Amal issue!

Post by 56G80S »

From memory, it's self extracting due to the strange internal and external screw threads. Try a search, I'm sure someone competent will have explained this sometime.

And they did, see Clive's entry in this thread (if the link works). It's the fourth post in the thread.

viewtopic.php?f=17&t=23715&p=194779&hil ... on#p194779

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G3L1946
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Re: Another Amal issue!

Post by G3L1946 »

Hi, thanks for reply and link which worked. Do I take it that you continue to undo the bolt ( forcing it past its desire to stop doing so ) so as to extract? An earlier part of the link mentioned a special tool ( bolt ) but I took this as not being relevant to a ‘55. Have I understood correctly? So as be clear, it’s an SR1 magneto on a 1955 G3LS. I really don’t want to proceed if I’m wrong and make a complete hash of it. Sorry if I’m a bit dense but old age don’t come alone!
Steve
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Re: Another Amal issue!

Post by ajscomboman »

You have it correct, the bolt undoes past the point it gets tight and this action removes it from the taper on the magneto. It's an awful idea and has caught many out first time round.
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G3L1946
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Re: Another Amal issue!

Post by G3L1946 »

Hi, thanks for that. It gives me a bit more confidence to pull the spanner harder! I’m wanting to remove it to change the springs and give it a good clean. Also, to gain access to check valve timing. Any further hints on doing that process would be very much appreciated.
Thanks, Steve
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Re: Another Amal issue!

Post by SPRIDDLER »

G3L1946 wrote: Mon Jan 17, 2022 9:48 am Hi, thanks for that. It gives me a bit more confidence to pull the spanner harder!
Before you do that and risk creating another issue try a sharp tap on the bolt head. Often when parts on a tapered shaft won't shift by applying progressively greater force a sharp tap will shock them into separation.
I’m wanting to remove it to change the springs and give it a good clean. Also, to gain access to check valve timing.
You may be over-worrying as from an earlier post you said that when operating the a/r manually it became stuck at the advanced position. In that case before digging deeper I'd flood the a/r mechanism with some releasing fluid (e.g. WD40) and keep working it manually to try to free it off. If it does free off and cures the kicking back/spitting when starting you've cured the problem so have no need to go further except to perhaps remove the assembly at your leisure to fully clean it and replace the springs if necessary.

If you want to check the valve timing this will help:

http://archives.jampot.dk/technical/Gen ... e_Dots.pdf

Later edit...
It's difficult to describe a 'sharp tap'. You don't want to hit so hard to risk damaging the mag internals. However, the best I can say is to imagine that for the a/r bolt imagine you are using a cobbler's hammer (not a large engineer's hammer) to crack a hazel nut without crushing the nut inside. ;)
Last edited by SPRIDDLER on Mon Jan 17, 2022 10:50 am, edited 1 time in total.
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G3L1946
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Re: Another Amal issue!

Post by G3L1946 »

Hi Spriddler,
Thanks for info. The springs look a bit suspect in as much as they look quite new but not very substantial. Possibly another quick fix previously performed? I’ve ordered replacements to make sure. The mechanism sticks slightly more in certain positions so a clean may be all that is needed. While attending to this I thought I would just check the valve timing if it only meant removing the housing to expose the cams. See if the correct dots/ numbers line up? I’ve encountered so many ‘ not quite right’ with this restoration that checking this would at least settle my mind that it was correct.

Post script.

Just read through link, very helpful, thank you. It would appear that I just need to ensure dots follow as per article and all should be fine. No need to remove cams , just check.
Regards,
Steve
Last edited by G3L1946 on Mon Jan 17, 2022 10:57 am, edited 1 time in total.
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