I would believe my Owner's Manual, stemar.<br /><br />With a 4 stroke, when in doubt use the higher octane petrol. But...check the Owner's Manual.<br /><br />Good luck.
The owners Manual for the 90 states 86 octane.<br />You can view the owners manula on-line at honda's website (www.hondamarine.com) in the owners section<br /><br />Nav
To confuse matters even more , here in Europe Research Octane ratings are used instead of Motor octane numbers. In Norway our "regular unleaded" is 95 oct RON.