Be aware that the HT centrifugal clutch does not have a slot cut into it's hub for the woodruff key. The only thing preventing it from slipping on the shaft is friction.
Folks have had issues with the clutch slipping on the shaft while climbing a hill or during hard acceleration. Others have had no problems what-so-ever.
It all depends on just how well the shaft and clutch fit to each other.
Since quality control with these China engines is a random phenomena that few folks actually believe really exists, the fitment is purely coincidental.
Some folks carefully, veeeery carefully grind a notch into the hub to allow a homemade key to work. It takes a Dremel tool and a few diamond cutting bits to accomplish.
silverbear has done it and has pictures of it in one of his threads.
I looked for it but could not find it within the time frame I have.
Here are a couple of threads on the centrifugal clutch: