The CR9EH-9 spark plug needs a 16mm or 5/8" socket.
18MM
5/8"
18 mm
11/16" (18mm) deep well socket
18mm My 2005 Kymco 250cc Grandvista / Grand Dink takes this plug and I use a standard 3/8" drive 18mm Deep socket when changing the plug because none of my other sparkplug deep sockets fit.
for a 2.4 ngk-tr55 plug
Ngk - dr8es-l
Use NGK MOdel # d7ea WITH A GAP SIZE OF 0.028
Other spark plug brands which cross-reference/interchange with the Champion QC12YC include: NGK: BCPR5ES Denso: Q16PR-U As for what applications the spark plug fits, it fits various European applications, such as BMW, Mercedes, and Saab.
I'm using NGK Iridium plugs, CR7EIX with the gap set to 0.7mm, as per the UK NGK website.
ngk brh7s
NGK BPM7A is the one you will need