I did some practical tests, and my cheapie 50 CCA battery [Weize YTX4L-BS] is able to spin The Bride’s starter motor at a similar perceptible speed as the larger 90 CCA Motobatt. This battery is standard equipment on many small bikes equipped with electric starters, including the Kawasaki Z125, Yamaha TTR125LE, and a whole slew of 50–90cc ATVs and scooters, so I’m going to assume it’s up to the task of starting a GX clone engine.
I put the torque converter housing on the engine and found that the little guy will nestle quite nicely between the motor and swingarm. So, I have a path forward and a new battery tray is in the works.
As for the Motobatt, I don’t plan on using a battery as large that for Bultakenstein, but perhaps I can keep it charged and in good shape until I get around to the Ducati-Aermacchi Special.