I have a 250 SHO. I've always ran mid grade fuel.I'm wondering if I will notice an improvement in performance with premium fuel. What say you?
I have a 250 SHO. I've always ran mid grade fuel.I'm wondering if I will notice an improvement in performance with premium fuel. What say you?
17 Ranger Z520c Black Out Edition
Yamaha 250 SHO
I tried it on my 250 sho basscat puma . Less performance from what I seen . Would not break 80 . 89 octane. 81 82 any day by myself .
89 non ethanol
12 lbs 9 oz caught on 4/28/1975 Lake Eufaula
I have seen the same results with different octanes other than 89...78-80 with 87 or 93 and 82-84 with 89 with my Eyra. i also can not find non-ethanal in 89 so I use ring free plus and everything is fine so far. I was told that it is better to run 89 with ethanol than one of the other with out ethanol.
Elwood....Bass Cat Strong
2020 Bass Cat Eyra
2020 Mercury 300R 4S (1E081080)
Hell Yeah!!!!!!!!
Engines now are made to use ethanol. The problem with it is that it's alcohol so moisture becomes an issue if it sits too long. Yamaha says to use 89 octane so whether it's non ethanol or not, that's what should be used. If the boat is used often really no issue, if it sits for extended periods may be.
2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.
I would consider a four stroke outboard a high compression engine. Higher-compression engines need the higher octane so that the fuel doesn’t pre-ignite in the combustion process and damage the motor. Octane slows and controls the detonation of the fuel during the compression and detonation of the fuel. So I would think 91 octane with or without ethanol would be allowable in a SHO.
X
I am running the 89 (with or with out ethanol) and Yamaha Ring Free Plus, just like the Yamaha tech told me to. I can also see a big difference in performance with a higher or lower octane regardless of with or with out ethanol. I also run my boat 2-3 times a week and neither tank will last over a couple weeks in the boat. I also only fill them half way (boat holds 54 gallons) and run them out alternately. Call your Yamaha Tech and ask him if you want a straight up answer. That is what I did. 122 hours on a 18 motor and not even a hiccup and I run mine hard. At 102 hours I had 8.6 hours at 1000-2000 rpm and 11.3 hours at 5000 - 6000 rpm and 1.3 hours at 6000 - 7000 rpm. So more time at full throttle than idle.
Elwood....Bass Cat Strong
2020 Bass Cat Eyra
2020 Mercury 300R 4S (1E081080)
Hell Yeah!!!!!!!!
What ever the owners manual says is what it is designed to operate on.
Steve McQueen "Le Mans"
Own the Champ! Life Long Petty Fan!
2003 ChampioN 2006 250 Merc. XB, Prop By Mark C.
2002 Ranger Okeechobee Special EvinRude Ficht 90 / 9.9 4-Stroke GLAD to have a Get me to the Dock motor maybe!
17 Ranger Z520c Black Out Edition
Yamaha 250 SHO
89 octane is whats called for on the 225/250 Yamaha SHO. The 200 recommends 87.
Why do some folks on the Mercury forum get into fights (and get banned), about arguing over octane? That higher octane actually damages the engine.