Thanks for the info on the spark plugs. I'll look into getting a few as well as a few spare parts (gaskets and such). Are there any items in particular with this motor I should carry in the parts box?

~$18USD certainly isn't cheap but it's not the most I've paid for a plug, the most I've paid for a spark plug is $65AUD for NGK R6120-105's back in 1999. The plug cap to suit was $65 as well. Good thing my bike only had two of them......