ORIGINAL: STUKA BARRY
That plug, NGK BPMR7A is an awesome plug for any of the Zenoahs, including the GT-80 twin.
I use them too on my Zenoah G62 but the B
PMR7A is a projected tip plug and will not work on the small Zenoah's as the piston will hit the tip of the plug.
So on the G23 you have to use the BMR7A without the "P" .