Re: Help trying to determine build year of a evinrude (lightwin) 4hp
Well, as I see it, 50:1 motors are those with needle bearing crank and rods (non-friction motors) '64 and later. Those with the bushings such as the Lightwins (friction motors) and such need a little more oil, because the fact that there is no needles at all. I say manufacturer's recemendations be damned. After all, OMC built 100:1 motors and payed dearly for it. So, are manufacturers recemendations gospel?
The TD model was built without needle bearings just as the 1970 Lightwin was, but it calls for 16:1 mix and some here say to run the Lightwin at 50:1. WHAT??? The clearances on the rods to crank are still basically the same, so what has changed? Not much. A big reason why so many TD's are still running today, is people who actually followed mixing instructions made them last. The 1952 Lightwin/JW is virtually built the same as the 1968 model, with the exception of some cosmetic changes in those 16 years, but the oiling instructions are different. I say the only thing that warrants less oil, is an improved design, not factory recemendations. I have a shattered rod and a scorched crank for this exact motor, because of too lean of oil mix, I'm sorry to say.
Myself, 24:1 is the leanest I would go, on a non bearing motor, but that's just my opinion.
Not to ruffle anyone's feathers here, but a wise man once told me that oil is the cheapest thing you'll ever put in an engine. First as being the least expensive fluid it'll consume and second, saving a lot of premature wear and costly repairs.
I think a lot of what's behind the change in oil mix recemendations in 1964 - 65 that a lot of people here talk about is the fact that the EPA and DEQ have beaten up on the manufacturers so much to the point, that they have came out and siad: "this is the mix your motors run on now" After all, it is these same people who wants Ford motor company to build an F350 to get 30 miles to the gallon. By the same token, these people want us to get our old smokey antique outboards out of the waterways. So when OMC decided in 1964 that motors run on 50:1, this most likely took the pressure off, from the environmentalists and the aforesaid government beurocracies. Later on, pressure got bad and these manufacturers are building four strokes, because more and more places are banning two stroke engines.
So as I see it, I think it's best to set a standard on oil mix, by the construction of the motor, not by what a sales brocure says.
