Calling all rivet counters, need O-ring info

[Eurocycleguy]

Putting together Cam chain tensioner on 750. I need a need O-ring that goes inside the Adjuster Cover and seals up the Adjuster rod.
In the Parts section, Table #4, in my 1974 GT American Owners Manual; the O-ring is ID'd as: OR gasket Part # 5513000766
In the Parts section, Table #4, in my 1969-70 SF (European?) Owners Manual; the O-ring is ID'd as: OR-2031 Gasket Part # 233M

I feel confident the OR in both descriptions means O-ring
I do not know what the 2031 denotes. Is that a code for sizing or a standard identification code?

Regardless I need to know what sized this O-ring is.
Thanks for your help.

 

[Ernesto]

Look here: https://www.thisoldtractor.com/o-rings_uni.html

Ernesto

 

[arancia]

There's a UNI standard nomenclature for non-metric sized o-rings used in metric-based applications, for example at

UNI O-ring standard specifications (metric) - O-ring cross reference - Technical information - Gregory Bender

UNI O-ring standard specifications (metric) O-ring cross reference Technical information on Gregory Bender's This Old Tractor

www.thisoldtractor.com

Size reference code	Decimal size in millimeters
Cross-section	ID

OR 2031 (OR2031)

1.78 mm

7.65 mm

which you'd translate into an american fractions of an inch size for your o-ring supplier (5/16, 1/16?)

 

[Eurocycleguy]

Look here: https://www.thisoldtractor.com/o-rings_uni.html

Ernesto

I was bad and asked the Forum before researching online. Thanks Ernesto.

 

[Eurocycleguy]

There's a UNI standard nomenclature for non-metric sized o-rings used in metric-based applications, for example at

UNI O-ring standard specifications (metric) - O-ring cross reference - Technical information - Gregory Bender

UNI O-ring standard specifications (metric) O-ring cross reference Technical information on Gregory Bender's This Old Tractor

www.thisoldtractor.com

Size reference code	Decimal size in millimeters
Cross-section	ID

OR 2031 (OR2031)

1.78 mm

7.65 mm

which you'd translate into an american fractions of an inch size for your o-ring supplier (5/16, 1/16?)

Thanks arancia.