# Oil to gas mix ratio?? 1999 50 HP Yamaha



## Captain WhupAss

A friend bought a Carolina Skiff with a 50HP Yamaha.. and called asking what the mix ratio should be. 
Does anyone know right off hand?


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## DOUBLE "D" & LV

50 to one


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## Captain WhupAss

Thanks Double D! That is what I told her, but just wanted to make sure.


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## Fido

I think even a 1999 Yamaha 50 had "Precision Blend". Look under the cowling and you should find an oil reservor - no need to add oil to the fuel. You can check with one of the local dealers and order an owners manual. Most of the Yamaha engines that required premixing the oil used a 100:1 ratio.


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## zulubravo34

Fido your an idiot all f ' in yamahas that are two stroke, before the year of 2000 DEFINITELY use a 50:1 ratio... your a ruhtard


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## lastcast

Man, talk about diggin up bones! Got a two year laugh out of that one.


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## X-Shark

I had a '98 C-90 Yamaha. The C designated that it was a premix motor. 50-1 or 1qt to 12gal. 1/2qt to 6gal


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## Wahookilla

I agree with Zulu and x shark. 100:1 is definitely wrong. Just sayin that these guys are right


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## hymarkdot

*50:1*

Since Yamaha came to the US the actual target ratio per Yamaha has been 100:1.The mix commonly used is 50:1 it is safer but dirtier and causes fouling of the spark plugs.The 100:1 ratio was an emission requirement for import. The following is an older article from a tech manual:


Conventional 2-stroke outboards mix oil with gas for lubrication. Modern techniques have enabled quality manufacturers to produce engines with closer tolerances. Some manufacturers continue to produce older technology engines that typically use 50:1, or twice as much oil. The 100:1 ratio means less oil required (producing) less blue smoke, smoother running and an engine with a longer life. Be sure to use only Boating Industry Association (BIA) certified 2-cycle oil in your new outboard. Yamaha pioneered 100:1 fuel/oil ratio in 1984.


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## X-Shark

> The mix commonly used is 50:1 it is safer but dirtier and causes fouling of the spark plugs.


With the oil I used in all those years of owning that '98 Yamaha C-90 I ran a oil that is no longer available. It was called Greased Lightning. I was a Red color. Looked the color of ATF. They haven't marketed it in quite a few years. It was the only oil I ever used in that motor except for 1qt and 12gals of gas. The motor had 438hrs on it.

That time it had the other oil put in it, it did smoke badly. I had ran out of the Greased Lightning. This motor didn't have the bellowing clouds of oil that you see at startup of old 2 strokes. Yes you sometimes saw a wisper of smoke when it was being flushed.

The motor had one sparkplug change @ 200hrs just to do it. It was not fouling plugs. It could troll for 4 or 5hrs at a time and never hickup, then hit the throttle and it would run perfect. One of the best outboards I ever had.
The Yamaha "Factory" repair Manual that included C-60, C-70 & C-90 said 50 to1 mix. My brother owns it all now in Tn.

Now.....There were motors that Yamaha built that year also that were not premix motors. They had a oil tank. This was a more expensive motor.
I bought that motor Jan 13 1998 from Emerald Coast Marine. Tobby was the salesman and Bob owned the business. That motor went for a dealer checkup at 25hrs and never saw a shop again. 3 waterpump changes, 1 sparkplug change, one thermostat change and the oil in the foot changed twice.

I did all the service and kept the records on it. Yes a hourmeter was installed on the boat as soon as I brought it home.


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## hymarkdot

I really just like to read the forum, for many years it has a lot of good info ,deals and some really funny s**t. But this one just seemed to catch me wrong. Alot of things we do our entire lives will work for us and us alone. The same thing for others will fail every time. All you can do is what the manual tells us, correct or not.The info i posted was intended for "fidos" benefit in reference to the statement:


"Fido your an idiot all f ' in yamahas that are two stroke, before the year of 2000 DEFINITELY use a 50:1 ratio... your a ruhtar"d "

If one were a Yamaha mechanic from the time the product was introduced to the US, a translation problem in all manuals would have been noticed throughout all specifications. The correct ratio from the factory is and has always been 100:1. The ratio can be modified up to 40:1. In the US we commonly use 50:1. The precision blends ratio varies from @90:1 to 130:1 This would be the system on an engine similar to the one we have been discussing. These are facts and not opinions and no offense to anyone.


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## Sequoiha

Now its my turn for my .02 for what its worth, since there are so many opinions and the name calling and such, i decided to look into this, several of you are correct about the 100:1 on most yamahas,, BUT this engine is not,,, according to the 1999 owners manual and the 1999 service manual for the C50tlrx the Break in ratio is 25:1 and the normal fuel to oil ratio is 50:1. Per Yamaha. so now we can quit guessing. :thumbsup:


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## appleguy

A 50:1 Ratio would be fine.
If you don't know what a 50:1 is?
Example: 1GAL Gas you add 3oz of oil or precisely 2.56oz oil to 1 Gallon of Gas.
You can buy a pre marked oil mixing cup from West Marine that has the correct mixing ratios from 10:1 - 100:1 it's a very handy tool to have when you pre-mix it yourself.


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