Be sure to BLOW that cavity out before you pull it.

Gottatake the tank off unless its had the chrome pulled or modified.
Yaz ottsta have the tool in the kit on the bike.

Handbook illustration2

Note: that's from the owners manual available in the tech section.

Probably too late to help the OP, but I'll add this for reference to any future searchers:

I've found that the fuel tank does not need to come all the way off the access the spark plug.  Here's what I do:

Here's what I do:

1.  Remove the seat.

2.  Remove the two bolts from the rear of the fuel tank.

3.  Remove all lines (fuel and vacuum (if you still have one)) from the petcock.

4.  Move the fuel tank back a bit, then prop up the rear of the tank with a short section of 4" X 4".  This will keep the tank out of your way.

5.  Remove the port chrome beauty cover.

6. Slap a wobble adapter onto your 3/8" drive ratchet.  Pop an 18mm deep-well socket on the adapter and you've now got access to the spark plug.

Note that, when using this method, I do not have to disconnect the speedo cable or the electrical connector.

IHTH!