AsalamOAlikum everyone, hope all of you are doing well. I wanted to write a few words about YBRs "missing issue" and explain to you that it is not an issue at all, but the bike's genetic design.
YBR's 125cc engine produces 10.70hp @7500 RPMs, that is the max power it will produce at that point in any gear. The torque figure is max 7.67 ft-lb @6500 RPMs but that isn't important here, back to the Issue.
The reason that bike starts missing after 8000RPMs is by design, the company has made it's CDI in such a way that it will provide low ignition beyond 8000RPMs, as if the bike wants you to shift. The reason the company did this is because the bike simply cannot produce more power beyond 7500RPMs, anything above that and both horsepower and torque takes a dip, the bike cannot breath efficiently, and hence it starts missing. People think it is an issue and they try to fix it, some people install Junoon's CDI to fix this "issue" while some remove air ducts, others install Iridium spark plug and what not but they're just wasting their time.
Hence please shift your gear at 7500 RPM and stop mistreating your YBR. It's a fun sports commuter which is made for easy riding, please leave the tiny engine alone and handle it with care. I hope this will have clarified to you that the missing issue is not an issue, it's by design.
Have a good day everyone. 
