Hello, I bought YB125 last year and convinced company to print me wiring diagram and technical specifications. I scanned it and I'm posting it for you.  
Images are in resolution from scanner, they all have 9.5MB.  
Preview: 
 
 
 
Links to big images: 
Wiring diagram (3.5MB) 
Key to diagram 
Technical specifications 1 
Technical specifications 2 
Technical specifications 3 
Technical specifications 4 
Technical specifications 5 
Technical specifications 6 
Technical specifications 7 
 
I hope it will be helpful to someone. If anybody has information about hacking ECU or other usefull information about EFI on YBR125, please post it. I discovered one thing, fuel injector make clicking noise that can be misidentified as too large valve clearance  
I'm wondering how strong alternator is? How much amperes can I safely drain from it? 
Is there way to hack EFI and reprogram it? 
Some information about diagnostic tool? Protocol, specification of diagnostic interface, etc... 
Removing catalytic converter? 
Baggage holder considerations?