Determining Battery Size

[Paul75]

Time for a battery! Ok, '79 650 Special. No front headlamp or indicators but I am keeping the electric starter. How do I work out what size battery I need? I want something as small as possible that will do the job,

Any help much appreciated as always,

 

[TwoManyXS1Bs]

Paul, start off with a forum search on: "Battery CCA"...