Well, I thought it was kind of weird that the NGK plug stuck out of the head so far, and when I pulled it out, the first 3 or 4 threads were black from being in the combustion chamber. I wondered if this plug is what was originally recommended by Yamaha, or if it is the closest equivalent that NGK sells... If I can get the manual, I'll find out for sure.
That's the other problem I'm having right now. I won an auction on Ebay for a manual, but the seller is in Tasmania, Australia and my emails to him keep bouncing back. I'm hesitant to send him money for the book if I can't contact him reliably...
david