force 120

[DJ. DJ.88]

I just bought a 1992 force 120hp, it has a vibration in mid range, (new prop) and it hunts in mid range between 100 and 300 rpm at 1500 to 3500 rpm. I idles fine and it will rev up to 4800 rpm, with know vibration. What octane of fuel should I be using?<br />Thanx for any info.

 

[MGuckin]

Re: force 120

DMJ88,<br />Welcome to the forum and congrats on your boat purchase.<br />You should be using 86 octane or "regular". A higher octane level is not required unless the motor has been extensively modified and even then, it would be usually just rejetted. You can read this article about fuels.<br />As far as the vibration is concerned, did this start when you changed the prop? If so, it may be a bad prop. If not try posting a question in the "Outboard Engine Troubles" section.