Hm, he could just buy 8 garden tractor batteries. Not exactly cheap, but not that expensive.
Agreed.
Well, that's a part of fun of life. After all, it is much easier to buy a working gasoline motorcycle than it is to dick around with strange motors.
Sometimes using scrounged parts helps. For example, I built a 10 HP phase converter for $45 worth os used components. A commercial one would cost me $600 plus freight shipping. Mine works just fine.
This may be the case with a 3 phase battery, inverter, phease converter and 3 phase motor powered "motorcycle", but not in general.
It's a matter of common sense related to the individual project in question.
Should I hire a licensed electrician to replace an electrical outlet? DIY is a better option for most.
Should I build a $10 digital clock myself? Not really.
Should I build a $45 phase converter instead of $600+shipping phase converter? Sure.
Should I buy a cheap 3 phase compressor and repower it for single phase, inctead of buying a more expensive single phase compressor? Why not.
Should I build a homemade lathe using hand files and home castings? That would be stupid.
Should I build a homemade water slide? Why not.
It's all about specific details of specific projects.
That statement is too broad. The guys who made compressed homemade air dryers are way ahead, money wise and likely functionality wise.
That would be my approach if I was tasked with "making an electric motorcycle". All it needs is batteries and motor and speed control.
That would also involve an incredible amount of time needed to make sensible operator controls. (start, stop, accelerate, etc)
It is not the kind of project that I would undertake.
i