What fuel should I use in 4 stroke yamaha

 Hey all, I've recently bought a boat and it has a 60hp 4 stroke yamaha on it, the guy I bought it off said he had been using 98 unleaded in it, I've read that they are designed to use 91 unleaded, my question is do I continue using the 98 or just use 91?


sunshine's picture

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Date Joined: 03/03/09

I use 91

Mon, 2022-02-07 08:56

And get a nautical mile to the litre with my 225.   98 totally unnecessary  

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Date Joined: 28/05/15

 1nm per L with a 225 is

Mon, 2022-02-07 09:39

 1nm per L with a 225 is insane economy 

sunshine's picture

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Date Joined: 03/03/09

Been like that since new.

Mon, 2022-02-07 13:39

6.8 Seaquest......regularly head out from Woodies to the 50's for a round trip distance of between 48 and 50nm for a fuel use of perhaps a litre more than distance travelled .....I try and sit on 3200 revs or around 23 knots. Economy drops if I wind it right up....increases to around 1.2 litres per nm but why hurry when you don't need to 

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Date Joined: 10/05/20

Thanks

Mon, 2022-02-07 09:01

 Thanks for your reply, I'm guessing changing to 91 won't do any harm after using the 98

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Date Joined: 24/12/15

fuel

Mon, 2022-02-07 09:19

 I have a 65lt in floor tank and was advised to use 98 as 91 dies quicker you never use 65lt in a trip and you are just topping up fuel so to keep your fuel fresh I use 98. The cost is not that much and my fuel is good to go.

 

little johnny's picture

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Supposed to use 91

Mon, 2022-02-07 15:18

Every now and again I run 95 to blow it out

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Date Joined: 28/05/15

 I'm usually the same but

Mon, 2022-02-07 18:32

 I'm usually the same but with the price of 95 lately it makes me lean towards 91 especially if I have to fill the prado (150L) up at the same time.

Faulkner Family's picture

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Date Joined: 11/03/08

 Only ever used 91 . Never

Mon, 2022-02-07 18:09

 Only ever used 91 . Never had any problems at all. 50nm on 70 litres in a 140 Johnson running at around the 4500 rpm

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RUSS and SANDY. A family that fishes together stays together

straith's picture

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Date Joined: 25/11/13

+1 91 is fine

Mon, 2022-02-07 19:53

 but as previously mentioned chuck a load of 98 in occasionally 

Jackfrost80's picture

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Interesting comments. What is

Mon, 2022-02-14 14:41

Interesting comments. What is the benefit of chucking in a load of 95 or 98 every so often?

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If catching wrasse is cool, consider me Miles Davis

Faulkner Family's picture

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Date Joined: 11/03/08

 From what I have been told

Tue, 2022-02-15 19:00

 From what I have been told it supposedly cleans out the injectors.  Never tried it myself 

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RUSS and SANDY. A family that fishes together stays together

Posts: 138

Date Joined: 24/11/10

yep 91

Tue, 2022-02-15 18:47

 i bought a brand new 90HP yamaha 4 stroke a few months ago.

 

Was told by chivers marine to use 91.

 

Still monitoring my fuel economy , but i am using at least 50% less than my old 70HP 2 stroke :) getting around 1.3 NM per litre.