ORIGINAL: SJN
Setting the valve clearance to zero seems like a very bad idea to me.
How mch have you run your engine ?
Ok. Set your valve clearance at your preference.
Check the clearance when engine is very hot and after a full tank, and then let me know the clearance. Then maybe you will change your opinion.
In a gasoline four-stroke cylinder the expansion of cylinder and head is greater than the valve rod pushers. I've learning this lesson servicing Saito gas engines, and always i set clearace close to zero.
Also i've received a tech note from the manufacturer with this recommendation
Best regards