G2 crankshaft sprocket spacer distance piece

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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G2 crankshaft sprocket spacer distance piece

Postby Richard Hyatt » Sun Feb 10, 2019 7:36 pm

Hi all , 1962 G2
Does anyone have the distance piece that goes between the backside of the crankshaft sprocket and the main bearing please ?
It is used to space out the sprocket to align the crank sprocket with the clutch basket sprocket.
Thank you
I have a single row chain by the way , I did the clutch hub up snugly against it's shoulder on the gearbox shaft , so I'm pretty sure the clutch baskets in the right place.
Just need to align the front crank sprocket and allow end float on the crank

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Re: G2 crankshaft sprocket spacer distance piece

Postby clanger9 » Sun Feb 10, 2019 9:10 pm

There shouldn't be a spacer there - occasionally there might be a few thou of shims (at the most).
The sprocket sits directly against the main bearing, but you have to fit it the right way round. Something I found out the hard way...

Here's a diagram:
viewtopic.php?f=16&t=23604#p194020

Here's a picture (duplex sprocket):
viewtopic.php?f=15&t=22452&start=20#p184422

Here's a thread with all the gory details:
viewtopic.php?f=15&t=17322

Summary: my bike originally needed a spacer (even with the sprocket the right way round), but that was because the main bearings weren't fitted correctly. With the main bearings in the right place, no spacer was needed.
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: G2 crankshaft sprocket spacer distance piece

Postby Richard Hyatt » Sun Feb 10, 2019 9:51 pm

Thank you for the thoughts,
Certainly our sprocket was on the wrong way round, and we've corrected that (thin boss towards the bearing track)
Now I need to align the primary chain by bringing the crank sprocket out a bit by this 041091 or similar.

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Re: G2 crankshaft sprocket spacer distance piece

Postby clanger9 » Sun Feb 10, 2019 10:05 pm

Hi Richard,

Check the full thread. Despite being mentioned in the manual, 041091 doesn't seem to exist.

If your sprocket is definitely the right way round, your main bearing is in the right place, you've got the right gearbox mainshaft and the sprockets are still misaligned, then you can pad the crank sprocket with some DIN988 shims:
viewtopic.php?f=15&t=17322&start=10#p155684
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Posts: 62
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Location: Dorset

Re: G2 crankshaft sprocket spacer distance piece

Postby Richard Hyatt » Mon Feb 11, 2019 11:11 am

Thank you for this,
Hopefully thin boss to the bearing is correct! It looked that way round in the drawings I found.
As far as I know the gearbox shafts are ok , I wouldn't really know if they were or weren't, it hasn't been on the road for ages by the previous owner , so I'm hoping it's correct.
We have a single row primary chain , your picture shows duplex , hope mines correct !
I'll explore those shims , that's all I can do.

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Re: G2 crankshaft sprocket spacer distance piece

Postby clanger9 » Mon Feb 11, 2019 5:55 pm

Richard Hyatt wrote:Thank you for this,
Hopefully thin boss to the bearing is correct! It looked that way round in the drawings I found.
As far as I know the gearbox shafts are ok , I wouldn't really know if they were or weren't, it hasn't been on the road for ages by the previous owner , so I'm hoping it's correct.
We have a single row primary chain , your picture shows duplex , hope mines correct !
I'll explore those shims , that's all I can do.


Yes, simplex is fine! Mine just happens to be duplex.

How far is the misalignment? You can correct up to maybe 3mm with shims - beyond that you'll start running out of thread on the output shaft...
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: G2 crankshaft sprocket spacer distance piece

Postby Richard Hyatt » Mon Feb 11, 2019 6:10 pm

Probably about 1/8" which is about 3mm so should be ok with thread , thank you for this.
It certainly is a voyage of discovery , this bike !

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Re: G2 crankshaft sprocket spacer distance piece

Postby clanger9 » Mon Feb 11, 2019 6:16 pm

Excellent. Hopefully it will all go together correctly!
These Lightweights are tricky, aren't they? ;)
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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