What kind of battery does Sepp Koch use in his bikes?

They are small but have to be powerfull to start the engine.

I have build a bobber/ streetracker with the battery in front of the rear wheel but it is a little to big .
When I lean over to much  some times it touches the street a bit. ( the foot pegs also they are allready higher mounted)
I read and speak German a bit .

Danke schön

Harry aus Holland

Danke schön.

They do have enough starting power? I looked one up on the internet.
Hawker SBS8 7aH, original battery 18aH I hope it works.


Greetz Harry