Working on a '70 AT1 and need a battery. Online I see it as a Yuasa 12N7-3B, measuring 5.31"x3"x5,25". But I also see a Motobatt AGM battery (which I did not make note of either the model or physical size- sorry  ). 

I did a search of the site here to see what others are using and I did see the Motobatt name but no model. The reason I ask is that the one I get pointed to is definitely a different size than the Yuasa. Don't need one that doesn't fit! 

Appreciate any suggestions! 

Motobatt MB9U is the sealed equivalent, and the size looks almost identical to your measurements.

To confirm Alan's results:  www.motobattbatteries.com/motorcycle-bat...nduro-1969-1971.html

The Yuasa 12N7-3B you mentioned is only rated at 70 CCA, so might not crank the engine with the electric start.
Agop uses the Motobatt which is rated 140 CCA on his AT1-E with a 175 top end and it will crank that when warm.

Thank you all for the replies and information, especially the site info that confirmed the sizing and cold cranking amps. I'm not at the point of needing it yet, just getting things lined up.

Thanks again guys!