gas oil mix ratio on 15 yamaha

D

danl

Member
Hey,

On my 14' grass boat i have a 2003 yamaha 15 hp, i bought it 2nd hand and the guy told me it was 50:1 mix so that is what i've been running. Now i've been fouling plugs, and have a hard time ideling with out the engine coughing and smoking, when im full throttle i have no issues. So i've been searching on line, and i see that yamaha calls for 100:1, as well as finding posts on other forums about 100:1 being to lean for an engine that will mostly be run at full throttle?

i noticed a post where the guy was using a 100:1 premix oil like amsoil, but mixing it closer to 80:1...


I was just hoping to get some input as to what some of you guys are useing for oil, and ratio?

Appreciate any advice you coul lend!

Thanks!

Dan
 
are you using yamaha 2m ixing it 100:1 or does yamaha make a specific oil for 100:1 mix applications?

thanks

Dan
 
I've got a three Yamaha on my mmbgf and use the advised 100:1. An Omc guy suggested that he'd never do that, and that a two stroke needed 50:1. But it is obvious from what Yamaha has spec'ed and their success 100:1 from now on would be advisable.
FRank
 
'yamalube' is what yamaha calls all of its oil and lubes, but specifies it by '2m' for 2 cycle '4m' for 4cycle, i just didnt know if they had a different 2 cycle oil specifically for 100:1
 
100:1 on my 15 yamaha, run Pennzoil full synthetic 2 stroke oil, startron, and ring free.
 
I bought a 2009 15 hp Yamaha,, the manual says 100 to 1,, the dealer told me 50 to 1. Was reading on line that Yamaha was striving towards 100 to 1 because of environmental concerns. Ive been running 50 to 1
 
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I've had a 15 HP Yamaha for years. Always mixed it at 50:1, a bit more smoke but never fouled plugs. Used it to backtroll for walleye. I always mixed the gas in a jerry can, never in the gas tank.
 
Dani, JustMHO but I would never mix at any leaner than 50:1. I know people get by with it but OMC backed off on it real fast after motor failures. Plugs are cheap and easy to replace. Pistons are not. But then I probably am just an old fart (HuntinDave you out there?) Good luck and I am open to opinions from all, just probably won't change my ways. After all you asked;>)
 
I was told 50:1 for the first three gallons and then 100:1 thereafter. That was from the dealer. The manual says very similar.
 
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Plugs are cheap and easy to replace. Pistons are not. But then I probably am just an old fart (HuntinDave you out there?)
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Yep, and I have been reading this thread with genuine interest. I too have a "new left over" 15 HP Yamaha and broke it in on 50 to 1 mix. I had told Tom I was staying at or near 50 to 1 while keeping a close watch on plug fouling. I have yet to pull the plugs but it starts right up so the plugs can't be in too bad of shape right now. The last tank of gas I did lean it out to 64 to 1 mix.

The way I figure it is much like Tom in as much as ; If it don't foul the plugs (or piston rings) more lubrication is better than less lubrication.

Right now I plan to stay on the 64 to 1 ratio. I have run about twenty [/font]gallons of fuel thru my engine to date.
 
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These motors definitely had some problems because of the 50:1 vs 100:1 They in fact were trying to stay ahead of EPA standards when they came out. They rand fine but it was mostly when they sat unused some of the internal parts of the engines were not lubricated enough. When not used regularly many had problems. I usually mix somewhere between 50 and 100 and have had no issues at all with my 15hp Yamaha two stroke. Its a great little motor.

Tony
 
Danl,
the idle could be related to other issues on top of the plug fowling. Have you had the plugs out.
How old is the gas you have run this year.
How much carbon is on the piston tops and inside the cylinder.
Not trying to overwhelm you just pointing out that there are a couple of places to check for symptoms and to avoid getting tunnel vision on the trouble shoot.

SeaFoam has worked well for many to clean up a rough idle due to carb issues that are minor. A can is a lot cheeper than a carb rebuild if you have to pay some one. Try a dose with some fresh gas and a set of plugs.
 
One more thought to just muddy things a bit more- Too much oil will displace fuel in the air:fuel ratio and will make the motor run LEAN. Think about that one for a bit boys and girls. I do have a lot of respect for Yamaha as a builder of motors and motorcycles but we all make some mistrakes.? !
 
Yep, and I have been reading this thread with genuine interest. I too have a "new left over" 15 HP Yamaha and broke it in on 50 to 1 mix. I had told Tom I was staying at or near 50 to 1 while keeping a close watch on plug fouling. I have yet to pull the plugs but it starts right up so the plugs can't be in too bad of shape right now. The last tank of gas I did lean it out to 64 to 1 mix.

The way I figure it is much like Tom in as much as ; If it don't foul the plugs (or piston rings) more lubrication is better than less lubrication.

Right now I plan to stay on the 64 to 1 ratio. I have run about twenty [/size][/COLOR][/font]gallons of fuel thru my engine to date.[/QUOTE]

Dave, Did you get the motor on your way through Ohio? Also, you running out the gas in the carb after every trip? The lead mechanic where I bought mine told me that's the best thing to do on these 15hp.
 
The gas is brand new, im assuming that i have carbon build up so i bought a can of valvtect decarbonizer to spray in there, hopefully between that and the oil change ill be running smooth.

Thanks guy, i appreciate the input!


Dan
 
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