100:1 fuel mix ???

fishfeatures

Senior Chief Petty Officer
Joined
Mar 29, 2011
Messages
743
I am servicing a 4hp 1988 2 stroke for a mate which hasn't been ran for a few years. I mixed the fuel for it at 50:1 but there is a decal on the side of the motor which states 100:1. Now i'm thinking this is too lean of a mixture and my mate being a tight wad would rather mix it at 100:1 as it'll save him buying 2 stroke oil as often :facepalm:

Is 100:1 ok or will i make him go with 50:1 and is it normal for yamaha's to suggest 100:1? I'm an OMC fan and all mine were to be mixed at 50:1
 

99yam40

Fleet Admiral
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Sep 7, 2008
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8,851
Re: 100:1 fuel mix ???

100 to 1 does not leave much oil on shiny internal parts between run times so it could rust up crank and bearings and ring/cylinder.

But should run fine
 

JB

Honorary Moderator Emeritus
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Mar 25, 2001
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Re: 100:1 fuel mix ???

Those Yamahas seem to work okay on 100:1, but OMC had very bad results when they tried 100:1 in the 80s. They ran okay but stored for any length of time they rusted internals. OMC abandoned 100:1 and retrofitted to 50:1.
 

Capt Ken

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Jul 30, 2002
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2,269
Re: 100:1 fuel mix ???

100:1 is perfect for trolling or if you idle a lot with a 2 stroke engine. 50:1 is ideal for high rpms. That is why engines like to foul plugs when the idle for extended periods with premix. Thus the reasoning for oil injection on most engines now.
 

fishfeatures

Senior Chief Petty Officer
Joined
Mar 29, 2011
Messages
743
Re: 100:1 fuel mix ???

100:1 is perfect for trolling or if you idle a lot with a 2 stroke engine. 50:1 is ideal for high rpms. That is why engines like to foul plugs when the idle for extended periods with premix. Thus the reasoning for oil injection on most engines now.

Ah now i see.... thanks guys....great info bit of info there...
 
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