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CC Hurl

Oil mixture on 2 stroke 25 HP Yamaha

12 posts in this topic

This one seems to goofy to be true so i need some help in understanding this.

I just picked up this motor and this is no joke, but the manual say's to mix the gas 100:1. This is not what they are saying to break the motor in with, but to run it at this all the time.

Is this true or am I missing something? My Merc was 50:1 and I thought that was rich. 100:1 seems like it would be mud that I am running thru it.

Anyone seen this before and why so rich on the mixture?

I feel stupid asking this, but figured maybe someone can fill me in on the concept of 100:1 mixture. 100:1 would be more oil correct?

Maybe you know someone who has the same motor and can let you know what they mix there's at.

Thanks

Hurl

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Think about this for a minute . 50:1 is 1 part oil and 50 parts gas , so 100:1 is 1 part oil and 100 parts gas , hardly any oil at all , or 1 gallon of oil per 100 gallons of gas . Yes this is correct . For break-in sometimes it is a richer oil mixture , 1 part oil per 25 parts gas .

Make sense ??

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Yes it does make sense, but 100:1 mixture? I have never heard of such a thing in a boat motor unless it's for the break in period.

I just got back from were i purchased the motor and he told me it is a California emisions thing and that i should run it 50:1 once done with the 100:1 break in period.

I am still confused and may just call Yamaha myself on this one.

I have a tendacy to follow the Manuals instructions and it say's 100:1.

Now the guys i purchased it from tells me you can burn up a motor if it's mixed to rich.

Thanks for your input BudMan,

Hurl

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This one seems to goofy to be true so i need some help in understanding this.

I just picked up this motor and this is no joke, but the manual say's to mix the gas 100:1. This is not what they are saying to break the motor in with, but to run it at this all the time.

Is this true or am I missing something? My Merc was 50:1 and I thought that was rich. 100:1 seems like it would be mud that I am running thru it.

Anyone seen this before and why so rich on the mixture?

I feel stupid asking this, but figured maybe someone can fill me in on the concept of 100:1 mixture. 100:1 would be more oil correct?

Maybe you know someone who has the same motor and can let you know what they mix there's at.

Thanks

Hurl

Looking at the manual for a 1989 Yamaha 15hp 2-stroke, it says 25:1 during break-in and 100:1 after break-in for normal use. The motor has a 100:1 decal right on the front of it. And, no, 100:1 means LESS oil...1 part oil to 100 parts gas. On my mixing chart on the wall of my garage, that means 8 ounces (1/2 pint) of oil per 6 gallon tank of gas. All my other motors have been 50:1 (1 pint oil per 6 gallons of gas). I tend to follow the manual.

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H2O is right 100:1 is less oil then 50:1.

I'd go with the manufactures suggestion as well.

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We run a bunch of 15hp. yamahas in various years from 2002 to 2005 on our portage lakes and they are all 100:1.

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My 05' 25hp Yamaha calls for 100:1 mix. I broke it in with about 10 gallons of 24:1 mix Yamalube and then switched to synthetic. Now I run Amsoil Sabre Outboard at 75:1 or 80:1. I run WOT a lot so the little extra oil helps and the Amsoil Syn burns very clean. When the mechanic went over the motor when I bought it he said its best to run it on about an 80:1 mix.

Break the engine in with Yamalube to help seat the rings, then switch to a full synthetic.

Yep 100:1 is half the amount of oil than a 50:1 ratio. a 32:1 ratio is 4oz of oil per 1 gal of gas. 100:1 ratio is about 1.5oz oil per gallon of gas.

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I had a 15 hp Yamaha and I ran it 50:1 for a year and it seemed a little rich.

During the winter I bought a shop manual and gave her a once over and in the shop manual I, too, learned of the 100:1 mixture. I called a Yamaha dealer to double check this and he said "Yeah...all the way up to and including the 25hp models run 100:1.

So I pulled the plugs and ran 6 gallons through at 100:1 and chickened out and split the difference and ran it 75:1 for the last year.

I've always heard that the worst that can happen with a rich mixture is white smoke and fouled plugs. Seems like a fair trade for peace of mind.

We all know the consequences of too little oil. Too many to list.

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Thanks alot for all the replies. I have been educated.

This site is always good for that, and that is one reason of many i go here.

I love nature and all the things it teaches us as well.

Anyway you guy's have given me the answers i need for the mixture on my new 25 Yamy.

I am now concerned because i have ran about 10 gallons of gas at about oh... I am thinking 60:1. My tank still had 4 Gal. at 50:1 and i put in another 2 at 100:1. That said i am not exactly sure were i am at. I have ran the motor about 4 hrs. so far. It is still doing just fine.

I will do the math and add acordingly to reach a 25:1 ratio. Run that tank out and then go with 80:1 for the life of the motor. Feel free to let me know if i should do other wise.

Thanks again for you lesson.

Hurl

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You're on track! You should be just fine with what you've run so far for breakin.. they're good little motors that don't typically have much for problems. Run a tank through at 25:1 if that's what the manual says and then switch to 100:1 or the 80:1 you're planning.

marine_man

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If you have already run 10 gals. through at 60:1, I would just switch to 100:1 or 80:1 and forget the 25:1, being it won't be the first tank.

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If you have already run 10 gals. through at 60:1, I would just switch to 100:1 or 80:1 and forget the 25:1, being it won't be the first tank.

I agree with outfitter. After 10 gallons at 60:1 your motors broke in enough to go with an 80:1 or 100:1 mixture. I'd consider running a full synthetic like Amsoil Sabre Outboard.

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