If you have a Microquiet 4000, I believe the spark plug it uses is the Champion RN14YC (similar to the Onan plug). Tighten it to 13 ft-lbs. Gap is 0.025. This plug has a 13/16" hex drive.
If you have a different generator, then the information above is useless to you!
Alfred
2005 Sightseer with Workhorse, ReadyBrute Elite towing 2003 Honda CRV
Map below shows states where we actually camped.....