Cast mounting boss inside twin timing cover?

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oldsmokey
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Location: LONDON UK

Cast mounting boss inside twin timing cover?

Post by oldsmokey »

Morning all,

Just bought a Matchless twin timing cover with what looks like a tacho mounting boss cast inside and level with the mag gear. The outside of the case is smooth as standard but one could drill the appropriate holes from the inside and thread them etc.

I've only ever seen AJS and Matchless twins with exhaust cam driven rev counters so was curious if this was actually for a tach or something else?
Anyone know what years this feature ran on?

Many thanks,


Adam
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Last edited by oldsmokey on Wed Feb 13, 2019 1:00 pm, edited 1 time in total.
G15 Roy
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Re: Cast mounting boss inside twin timing cover?

Post by G15 Roy »

My Understanding this was 1959 twins only and was for rev counter trying to find the bits will be hard.
Roy
oldsmokey
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Joined: Tue Feb 13, 2007 3:52 pm
Location: LONDON UK

Re: Cast mounting boss inside twin timing cover?

Post by oldsmokey »

Thanks Roy. Sounds like a challenge. I have never seen one mounted on the timing chest so will see what I can come up with. I'll add it to the twin carb manifold 'to do' list.

It only took me ten odd years to find my first exhaust tacho drive so I'll see if I can do this one within the same time period:)
39speedtwin
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Re: Cast mounting boss inside twin timing cover?

Post by 39speedtwin »

No not that hard Roy, you only need an extended nut for the magneto with a slot in it, plus the drive that must be 2:1 as these are the only ones that are available as both clockwise and anti-clockwise. Plus Rev-counter head, so total cost would be about £450.00!
ajsph
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Re: Cast mounting boss inside twin timing cover?

Post by ajsph »

20190213_181653_1.jpg
Hi Adam
The timing cover you have is a pre 56 cover, it has the hole for the relief valve spring.Here is some picture showing a cover ready to use.

Poul
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ajsph
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Re: Cast mounting boss inside twin timing cover?

Post by ajsph »

20190213_180503_1.jpg
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oldsmokey
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Location: LONDON UK

Re: Cast mounting boss inside twin timing cover?

Post by oldsmokey »

Thanks Poul, that's really interesting. I've not seen one before mine. I've also never seen one on a bike to my knowledge. Any images of the fitted relief valve?
ajsph
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Re: Cast mounting boss inside twin timing cover?

Post by ajsph »

the relief valve was used from 52 to 55, from 56 to 60 there was no relief valve, and from 60 they used a new type valve.

Poul
20190213_220929_1.jpg
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