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 50:1 gas mixture for old 2-stroke?		  New Topic  Topic Locked
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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts
Initially Posted - 08/02/2015 :  11:04:29  Show Profile  Visit delliottg's Homepage
I just picked up an ancient Evinrude Lightwin 3 hp 2-stroke that's older than I am. It was built sometime in 52-54. I like it because it's light (32-34 lbs, I think the latter because it's a 20" shaft), it runs, and it was basically free. The guy I traded for it has been using TruFuel 50:1 premix in it (zero ethanol), but says he's used it very-very little. It starts right up and seems to run happily on it and he gave me another quart of it to use in it.

However, reading the literature that I've found online, they tell you to mix 1/2 pint of motor oil into a gallon of gas, which gives you a ratio of 16:1. This is from the actual manual that I found JPGs of here.

Is the 50:1 going to hurt it? I can always mix in a bit more oil to boost the ratio if necessary. I also know the same company sells 40:1 ratio premix as well.
David
C-250 Mainsheet Editor


Sirius Lepak
1997 C-250 WK TR #271 --Seattle area Port Captain --

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts
Response Posted - 08/02/2015 :  13:20:17  Show Profile
I'd do what Evinrude says to do and what they built the engine for. Frankly, I think the guy was lucky, although the engine may have suffered a little.
Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge
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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts
Response Posted - 08/02/2015 :  14:08:12  Show Profile  Visit delliottg's Homepage
I think you're right. I found this FAQ page about fuel/oil mixtures for Evinrude engines, and the group opinion agrees with yours.
David
C-250 Mainsheet Editor


Sirius Lepak
1997 C-250 WK TR #271 --Seattle area Port Captain --
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Voyager
Master Marine Consultant

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USA
5231 Posts
Response Posted - 08/02/2015 :  16:37:47  Show Profile
When in doubt, lubricate. My British Seagull Forty-Plus uses 8:1 but that's excessive for most 2-strokes.
Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain — Milford, CT
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GaryB
Master Marine Consultant

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USA
4275 Posts
Response Posted - 08/02/2015 :  19:21:55  Show Profile
Definitely 16:1. 50:1 will kill it shortly.

In the mid-60's the ratio went to 24:1 and then in the 70's (I think) the ratio went to 50:1.

Association Member

GaryB
Andiamo
'89 SR/WK #5862
Kemah,TX
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Dave5041
Former Mainsheet Editor

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USA
3754 Posts
Response Posted - 08/07/2015 :  13:38:20  Show Profile
The quality of oils has improved for 2stroke use, but the carb is still jetted for a 16:1 mix. I split it and ran my early 50's Johnson on 24-32:1 to reduce smoking until I sold the old Knockabout 16 after a decade or two with the engine still fine.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle
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Chief RA
Chief Technical Advisor

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USA
191 Posts
Response Posted - 08/11/2015 :  07:16:16  Show Profile
I think I would tend to be on the conservative side on this issue as well for a very old engine. For general info though, I will provide this input. In the 80's when my sons and I raced 2 stroke motorcycles extensively we did not use the motorcycle manufacturers recommendation for oil mix ratio's. We used the oil manufacturers mix ratios and so did all other racers. These air cooled motors are/were put in far more strenuous situations than a water cooled outboard is and they held up great. I tuned them and raced them and my motors went to both state and even national levels. Yes, my oldest son is a California state M/X champion and youngest one #3.
I currently run my 1989 Evinrude 15 hp at 50 to 1 and have for many years. Chief
COMPASS ROSE C250WK
Tall Mast, Wing keel
PORT CHIEF, Bodega Bay Ca.
IE,EE,FCC lic #1890
Edited by - Chief RA on 08/11/2015 07:18:31
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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
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