I removed the front fender, therefore the battery couldn’t be stayed. But I need to start the engine, so I tried to make a mounting stay for the battery.

I chose that L-shaped angles.

I adjusted the height and made a hole.

It turned out to be something like this.

Then I added diagonal stays for reinforcement.

Finished!

The engine started without problems. By the way, I forgot to remove the stuffing of exhaust pipe, so that was popped out. hahaha.