1996 Evinrude 9.9 premix ratio

sleddude

Cadet
Joined
Jun 26, 2010
Messages
13
I was always under the conventional wisdom that most 2 strokes required a 50:1 premix ratio.

Two years ago, I bought a 1988 yamaha 4 hp outboard and it had a sticker on it 100:1 which always made me nervous so I mixed at 75:1 to be safe.

I have the carcass of a 1985 evinrude 15hp and just noticed it also has a 100:1 sticker near the fuel hook up.

I just bought a 1996 Evinrude 9.9 2 stroke and there are no stickers on it and I don't have the manual. What is the correct premix? I bought it from a guy who had never used it because it came with a sailboat as an emergency motor. He cleaned the carbs and I hooked up fresh 50:1 mix and it started on the 3rd pull.

I ran it in a test tank and it starts and idles excellent, but falls flat at about 1/2 throttle. it goes full throttle with the choke on.

I am not very mechanical, so I will bring it in to have it serviced. However, I know if I mix the oil too rich, I will have similar fouling and rough running issues. If anyone can point me to the correct place, I would appreciate it.
 

hidef

Lieutenant
Joined
Aug 22, 2009
Messages
1,465
Re: 1996 Evinrude 9.9 premix ratio

Your 1996 9.9 engine requires 50:1 make sure the oil you buy says TC-W3 somewhere on the label. OMC tried switching to 100:1 in the 80s but it resulted in a lot of engine failures OMC issued a TSB recommending all engines without VRO use 50:1 premix. Your Yamaha should also be mixed 50:1 as a 100:1 is just not enough oil.
 
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