Length of an original 1961 G12/Model 31 gudgeon pin?

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Length of an original 1961 G12/Model 31 gudgeon pin?

Postby Roderick » Wed Mar 13, 2019 11:02 am

Can anyone tell me the LENGTH of the gudgeon pin from an original Hepolite piston for this model? I don't have one to measure outside an engine.

Rod

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby alanengineer » Wed Mar 13, 2019 12:54 pm

About 2 1/2" or do you want it exact

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby Roderick » Wed Mar 13, 2019 3:58 pm

Exact would be nice, Alan, as I have an engineer who's agreed to make/modify one for me & they do like exact measurement, do engineers. Many's the flea I've in my ear about it!

Best regards,
Rod

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby ajsph » Wed Mar 13, 2019 4:11 pm

Hepolite: 2.373 inch
Poul

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby alanengineer » Wed Mar 13, 2019 5:17 pm

My one seems a few thou longer, but, its in the piston and i have had to do some measuring and some sums

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby Yves.Astein » Wed Mar 13, 2019 5:24 pm

I am messuring 2.420 inch (61.48 mm) from Hepolite 15036 Article Number.


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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby Mick D » Wed Mar 13, 2019 5:39 pm

Hi

Surely it's better to measure the piston it's intended to fit - why guess?

Regards Mick

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby raffles » Wed Mar 13, 2019 7:35 pm

If you are going to measure the piston dont forget its the distance less a few thou between the circlip grooves
Tony

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby Yves.Astein » Wed Mar 13, 2019 7:38 pm

Yves.Astein wrote:I am messuring 2.420 inch (61.48 mm) from Hepolite 15036 Article Number.




Just to be clear, above I messured the pin not the piston.

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Re: Length of an original 1961 G12/Model 31 gudgeon pin?

Postby Roderick » Fri Mar 15, 2019 11:01 am

2.420" looks like the sort of round figure AMC engineers would have used so I am going to take a chance on Yves and "deutsche Teuchtigkeit"! (or is it actually "efficacite francaise", Yves?).

Many thanks Alan, Poul, Mick, Anthony & Yves for taking the trouble to help. Much appreciated.

Rod

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