# 1990 Yamaha 15hp oil ratio opinion



## ocbinva (Jun 24, 2016)

I have my first 2 stroke outboard but not first 2 stroke motor I have owned. Notice it smoked allot and has quite a bit of unburied oil in the test tub. The guy who I bought it from said it was a 50:1. I downloaded owners manual and bought a Seloc manual and both of those say it is a 100:1 ratio. I do know some ratios were changed by EPA back then. The guys I got it from family worked marinas and the motor has been babied. Any opinions? 50:1 will give good protection, less of a mixture will have less smoke. I even thought about switching to synthetic. Opinions are appreciated. 


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## ocbinva (Jun 24, 2016)

I just found another forum with this discussion. I cannot seem to erase my original post off of my cell phone app. Do not worry about answering this post unless you want to. I appreciate everybody's work they put into this forum it is full of great data

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## dahut (Jun 24, 2016)

Follow the manufacturers recommendations.

The following is for reference only:

Changes to bearings, materials and construction also accompanied any EPA requirements at the time.
For example, my Johnson/Evinrude manual is very specific about where the line is drawn. Engines from 1985 and later (including 15 hp) models are to use 100:1 mixing ratio for well broken in engines that see regular use. 
50:1 ratios were only called for if the engine is stored for long periods under high humidity, large temperature excursions, and sees constant high rpm's when it is used.

And don't use just any oil. The manual is also very adamant about using quality, 2-stroke oil with an NMMA rating of TC-W/TC-W II, depending on the model.
Using automotive multigrade and detergent oils was specifically verboten as it may lead to piston scoring, bearing failure or other engine damage.

Note:
100:1 = 8 oz. oil : 6 gal. gasoline 


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## perchjerker (Jun 24, 2016)

what motor is it?

that will matter as to the answer


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## ocbinva (Jun 24, 2016)

It is a Yamaha 15 horsepower model 15ld

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## perchjerker (Jun 24, 2016)

ocbinva said:


> It is a Yamaha 15 horsepower model 15ld
> 
> Sent from my SM-G920V using Tapatalk



what year?

the more info you can provide the easier it is to help you


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## ocbinva (Jun 24, 2016)

1990 Yamaha 15hp Model:15LD


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## nowgrn4 (Jun 24, 2016)

The thought of those main crankshaft needle bearings running 100:1 at WOT makes me cringe.

Screw the EPA. I'd run around 50:1. 2.7oz per gallon or 13.5 oz per 5 gal. container.

Soap Box time. If the EPA really gave a crap about MPG and pollution we could get vehicle's like the rest of the world gets. Example; The Miata C-X5 small SUV with Skyactive diesel. 176HP with a whopping 315 ft lbs of torque out of a little turbo 4 Banger. That will pull your tinny. 50MPG highway while not towing as well.

Think what would happen if the majority of drivers here were getting 50MPG like the rest of the world. Fuel tax revenues would be drastically slashed. As a gov agency high tax revenue is their real concern, Not efficiency's. The EPA is a joke.


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## wmk0002 (Jun 24, 2016)

Have you tried it on the water yet? Pretty much any 2 stroke ran in a barrel will smoke exponentially more than one on the lake. Then there is the possibility the motor hasn't been used much recently and has lots of old carbon it's burning off. 

I'd take it to the lake and run it wide open for a good amount of time using 50:1 and see how much it smokes when you then bring it back down to idle or midrange speed speed. I bet it won't be noticeable and if it were me I'd run the richer fuel/oil mixture to err on the safe side.


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## ocbinva (Jun 24, 2016)

Yea I thought same thing. The guy I got it from is meticulous about maintenance and it shows on this engine. I figured I would stick to 50:1 for the time being. I hope to have it out Saturday. I was going to convert the roller trailer to bunks first but I want to get it on the water. I have new seats and making a live well so I want to get it out and play with seat positions to get the best performance since Son and I are both over 200lbs each.


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## turbotodd (Jun 26, 2016)

nowgrn4 said:


> The thought of those main crankshaft needle bearings running 100:1 at WOT makes me cringe.
> 
> Screw the EPA. I'd run around 50:1. 2.7oz per gallon or 13.5 oz per 5 gal. container.
> 
> ...




Agreed, the EPA is a joke. But in the case of auto's, I kind of understand why we don't get the "cool" stuff here. Some countries have MUCH stricter emission standards than even our own EPA does. Problem is, manufacturers have a LOT more to deal with when it comes to marketing something, like, say maintenance costs, initial purchase costs, repair costs outside warranty, etc....and all of that adds into the vehicle's pricing and overall cost of ownership. Sometimes those costs put it outside what Americans are willing to pay, hence the marketing bean counters keeping that vehicle in non-USA markets. The Aussies have some really cool stuff over there, some of which I'd love to see here....but to market it here would put the cost of ownership higher than a cat's back.

I hate the EPA. Example. I'm working on tractors now, not as many outboards and boats. Got a Tier 4 tractor in the shop, about 35 hp, comes factory with a DPF (diesel particulate filter)-and of course all the stuff that goes with it, electronic controls, electronic injection, fly by wire, etc. One of the things about the DPF system is that if the DPF itself gets plugged, it will cause the EGT's to go through the roof (exhaust gas temperature). Left this way for any length of time, and the engine will destroy itself-burned pistons, broken pistons, etc. And that's what we have currently. An operator who ignored the warning lights and buzzers that were designed to tell you that it wants to regenerate (burn off the soot in the DPF). So, now we're looking at a repair bill of about $14,300. New engine, new DPF muffler assembly and all of the junk that's attached to it. The tractor was $20,000 brand new with the loader, 2 implements, and a trailer.

The EPA has totally and forever ruined diesel engines and I suspect that sooner or later they'll do similar with gas burners and outboards. They're meddling with small gas engines now too. Catalysts in mufflers for lawn mowers. Cat mufflers on 50cc scooters. What a joke. It is such a small number of those engines running around that it does not make any difference whatsoever, BUT it does a good job of screwing the owners and operators come time to repair them.


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## ocbinva (Jun 27, 2016)

ok got the boat out and ran it allot over the weekend. The 50:1 ration worked great and did not smoke at all once I got the motor up to speed to burn out the build up. Even though the manual says 100:1 I think I will stick to something close to 50:1 for the added protection.


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## turbotodd (Jun 27, 2016)

at 50:1, you likely will notice some black sooty junk running out of the prop area, either between the prop and the foot, or out of the prop itself. Perfectly normal. Sometimes the goo will throw people into thinking that the foot is leaking. Also will notice more goo and buildup in the exhaust outlet in the prop, and some soot on the exhaust hole at the back of the leg. Again no big deal. This stuff won't happen if it's mixed properly at 100:1.


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## Pappy (Jun 28, 2016)

dahut said:


> Follow the manufacturers recommendations.
> 
> The following is for reference only:
> 
> ...



Wrong!! 
About the only part of this statement that is correct is the storage/damage part. 
There was a service bulletin sent out to all dealers to remove the 100:1 stickers and have customers run all engines on a 50:1 ratio.


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## dahut (Jun 28, 2016)

You're right - a bulletin was issued in Sept 1988, recommending, and I quote

"... a fuel-oil mixture of 50:1 be used on all recreational motors previously recommended for 100:1, when the motors are only used periodically and during the time of non-use the motor is stored in an area of high humidity or wide-scale temperature changes or, if the motor is operated at constant high RPM.

A 100:1 ratio may be used on models so recommended after the engine is completely broken in, and if used frequently but not at a constant high rpm"

As you can see, 100:1 is acceptable according to the conditions I summarized earlier. It then goes on to talk about changes to bearings in 1985 and later 2-30 hp models with tiller which allows them to be operated at the 100:1 ratio. 

I did summarize, previously, to keep it short, but it came right from the pages. Make of this what you will; like I said, "for reference only."

If you have grief with the content of the manual, however, please take it up with Shawn Etheridge, Editor, of Clymer (R), and Primedia, publisher of Clymer manual B732, 6th edition,

PS Lets not forget my first statement, either (probably the best advice any of us ever receive):
"Follow the manufacturers recommendation."


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