I wasn't trying to be a smart *** But if the battery won't start it but it'll start with a jump, it's the battery.
Just like if it was your car/truck/tractor Whatever it is you drive.
They make everything like **** these days, just because it's new doesn't mean it's any good.

 

Hi again,

Before reading all your comments (thanks a lot for them) I decided to put a new battery. I bought a new black Yuasa and replaced that fuc***n' ugly yellow one I had, charge it and installed in the bike.

The bike started at the first button touch, as it should. Tested voltages and they all were fine. So, the problem was a bad brand new battery. Now I'm going to talk with the seller of the battery to see if I can get some kind of refund. It won't be easy because I've had it for almost three months while putting my bike on move again before some years without using it, but that's another question.

So, thank you very much for your answers, I've learned a lot from this post, and I'm very pleased that the problem has been just a bad battery.

So, I'm on the road again...



Thanks for your help and best regards,

 

Good choice on the Yuasa.
I usually get many years out of mine.