G80 Dynamo sprocket

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Re: G80 Dynamo sprocket

Postby clive » Wed Feb 10, 2016 11:54 pm

You still have not said what gearbox is fitted, could be the Burman B52 or AMC box or even the Burman CP box as the date of the bike says nothing about what has happened in the last 60 years, the first two ought to take the longer Dynamo. I am also wondering if you have the spacer fitted between the drive sprocket and main bearing, it is sometimes left out and the result is the Dynamo chain runs too close to the crankcase. This would make it seem out of line.
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Re: G80 Dynamo sprocket

Postby dave16mct » Thu Feb 11, 2016 10:56 am

Have a look at your gearbox number. If its the correct one it should be something like GB27B56 indicating a 1956 B52 Burman. Your dynamo should be E3N. The sprocket look correct on the ebay listing.

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Re: G80 Dynamo sprocket

Postby Phil H » Thu Feb 11, 2016 11:59 am

Yes the gearbox No. is GB27B56.
Should there be a spacer between the end of the dynamo & the chain case.
& yes the spacer between the sprocket & the main bearing was missing.
Thanks for that advice

Philo.

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Re: G80 Dynamo sprocket

Postby dave16mct » Thu Feb 11, 2016 1:14 pm

There isn't a spacer between the dynamo and chaincase. Your problem was probabely as Clive suggested, the missing mainshaft spacer. Is your dynamo an E3N?

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Re: G80 Dynamo sprocket

Postby Phil H » Fri Feb 12, 2016 5:01 pm

Ah!! there we go it's an EL3.
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Re: G80 Dynamo sprocket

Postby sztyga20 » Wed Jun 05, 2019 4:56 am

Anyone knows does that sprocket fit to my G3LS E3N dynamo? It looks different in comparison to 000725 in amoc spares...
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Re: G80 Dynamo sprocket

Postby SPRIDDLER » Wed Jun 05, 2019 8:06 am

It's a poor photo but the correct sprocket will have a keyway which I cannot see on the sprocket in your photos.
The taper inside the sprocket also has to match the taper of the dynamo shaft.

Keyway:

Dynamo sprocket 000725 (530x278).jpg


You are perhaps not aware that the correct sprocket is secured with a specific nut, lockwasher and circlip. The dynamo and primary chains run very close to each other. If the dynamo sprocket becomes loose the chains can (will) collide. One of the chains will almost certainly break and cause serious damage to the chaincase or clutch or bend the dynamo axle.

2018-01-24 Dynamo nut, washer, circlip 001.JPG


When you have fitted the dynamo make a mark on the dynamo body so that in future after the outer half of the chaincase has been fitted you can ensure that the dynamo remains in the correct lateral position. When our bikes left the factory there would have been a guide plate attached to the dynamo body to indicate correct lateral positioning of the dynamo but nowadays these are often missing.
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Re: G80 Dynamo sprocket

Postby Jdraper » Wed Jun 05, 2019 5:22 pm

Very useful picture. I was unaware of the special washer & circlip, although I had wondered why there was a strange nut with a groove on the dynamo. When I bought the bike in the 70's, it had been partially 'chopped' (no actual chopping thank goodness) with ape hangers and a king/queen seat as well as most original bits/tinwork missing! There's still a few bits of candy red paint sprayed over the black stoving - far out.

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Re: G80 Dynamo sprocket

Postby sztyga20 » Fri Jun 07, 2019 4:22 am

Thank You Spriddler, parts have been already ordered:)

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