18S Engine sprocket

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Woodland
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18S Engine sprocket

Post by Woodland »

Hi Guys,
I have a 1953 AJS 18S, can anyone tell me the correct number of teeth on the engine sprocket
Is it 21 teeth to drive the clutch and 17 teeth to drive the dynamo?
I have looked in the parts book and the part number is 014021, but it also mentions that alternative engine sprockets can be supplied?

I just want what was standard when they built the bike
Also any idea where to get a new one? Maybe e bay?
Gary
SPRIDDLER
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Re: 18S Engine sprocket

Post by SPRIDDLER »

Your Spares List shows the standard one
http://archives.jampot.dk/book/Spares_l ... s_List.pdf
shows the number of teeth as 21 on 014021:
Sprocket - engine 1953.jpg
The dynamo and engine sprocket are one and the same piece so no alternative dynamo teeth option.

Others teeth sizes are comp options.

Available normally from club spares but currently out of stock. Maybe try an ad in the Jampot 'Wanted' section.
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Mick D
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Re: 18S Engine sprocket

Post by Mick D »

Hi

Also try Steve at AMC Classic Spares:

http://www.amcclassicspares.com/

Regards Mick
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Rob Harknett
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Re: 18S Engine sprocket

Post by Rob Harknett »

Check the primary chain length, number of links required to suit number of sprocket teeth, if you change the sprocket
Woodland
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Re: 18S Engine sprocket

Post by Woodland »

Thanks for the informtion guys, think I have spied one for sale on e-bay
Gary
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Duncan
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Re: 18S Engine sprocket

Post by Duncan »

Woodland wrote: Wed Oct 13, 2021 5:39 pm
Is it 21 teeth to drive the clutch and 17 teeth to drive the dynamo?
Hi Garry, it sounds like you have an earlier engine sprocket fitted, the dynamo drive was 17 tooth to 1948 and 21 tooth from 1949 on, this allows the dynamo to kick in at lower revs.
Woodland
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Re: 18S Engine sprocket

Post by Woodland »

The one that was fitted has 21 teeth to Dynamo and 21 teeth to clutch.
I have seen one for sale that has 21 teeth to Dynamo and 17 teeth to clutch, is this the correct one?
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clive
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Re: 18S Engine sprocket

Post by clive »

no the correct one for a 1953 18S road model is 21 clutch 21 dynamo. The 17 teeth to clutch is for a trials bike and would be very undergeared for your 500
clive
if it ain't broke don't fix
SPRIDDLER
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Re: 18S Engine sprocket

Post by SPRIDDLER »

Woodland wrote: Wed Oct 20, 2021 4:49 pm The one that was fitted has 21 teeth to Dynamo and 21 teeth to clutch.
I have seen one for sale that has 21 teeth to Dynamo and 17 teeth to clutch, is this the correct one?
No. See the spares list extract in my reply last Wednesday...........
SPRIDDLER wrote: Wed Oct 13, 2021 6:20 pm Your Spares List shows the standard one
http://archives.jampot.dk/book/Spares_l ... s_List.pdf
shows the number of teeth as 21 on 014021. Other teeth sizes are comp options.
Sprocket - engine 1953.jpg
The dynamo and engine sprocket are one and the same piece so no alternative dynamo teeth option.

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clive
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Re: 18S Engine sprocket

Post by clive »

Just to be clear all the sprockets listed above would have a 21 tooth drive for the dynamo and the listing refers to teeth on the primary drive side of the sprocket.
clive
if it ain't broke don't fix
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