ORIGINAL: atul
YS definitely has a special plug for this purpose and it is not inexpensive. I paid 1600 JPY (about $18) per plug direct from the factory. You can order plugs and other parts direct from the factory as well. The web-site is yspower.co.jp. I got 5 spare plugs but have not had one fail yet.
I would suggest you stick to the genuine YS part.
atul
Atul,
It is not a specialized plug. YS does not make these plugs. It is built to certain specifications and other plugs do meet this requirement. There are several plugs out there that will work just as well as the one YS sells. They really aren't any less expensive, but they will work if the other plugs are unavailable. It kind of like saying you have to run a YS glow plug in the non CDI engines. There are others that work just as well.
Arch