Scooterotica

Want to add a set of indicators to a Gp non battery model, my question for the electric wizards among you is which power rating is needed, only running 4 led indicators which the rating is 1.4w per lamp, will be using a small Yuasa alarm battery in the toolbox, they vary greatly from 1.2 amp/h through to a whoppping 9
Cheers

Those indicators are going to draw about 0.5 amps; that's all.
Theoretically you could run a 0.5amp/hour battery for 1 hour continuously but it doesn't work like that as no battery/circuit is 100% efficient. Go for at least 2amphour battery.

Are you intending to add a charging circuit to keep the battery topped up while the engine is running?

yes, will be running through a vespa regulator to top up the charge

You have other options: if it's just indicators you can stick with ac and not have a battery, if you're wanting dc you could use a mod-charger. I've found the alarm batteries are ok but don't last long (either they don't like the cold and vibration or the charge is a little unsteady for them).

Im using a compact wet motorcycle battery exide ytr4a-bs ill post a pic later

I have a 5Ah and a full DC setup including headlamps. Hid the battery in the under-seat tool box. Piaggio Ape rectifier unit charges the battery. If you don't wish to disturb the stator or existing wiring, any 4 pin Honda scooter rectifier would also do your job.