Gas Oil Ratio for Evinrude 88 Special

Optimizing the performance of Boston Whaler boats
Buoy
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Gas Oil Ratio for Evinrude 88 Special

Postby Buoy » Tue Sep 05, 2017 11:43 am

Per the Seloc Johhson/Evinrude Outboards Repair Manual, the gas to oil ratio should be 50:1. Is this the prevailing ratio in practice, or do some prefer a richer ration of perhaps 30:1? The engine is a 1993 Evinrude 88 Special.

Thanks.

Joe 15 SS LTD
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Re: Gas Oil Ratio for Evinrude 88 Special

Postby Joe 15 SS LTD » Tue Sep 05, 2017 12:41 pm

More is not always better. You can have carbon build up faster, foul plugs more often. to name a few things.
Others may chime in with other concrens.

jimh
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Re: Gas Oil Ratio for Evinrude 88 Special

Postby jimh » Tue Sep 05, 2017 2:49 pm

I'd stick with 1:50 for oil-gasoline ratio, but use a modern quality oil with low-carbon, low-ash, and additives. Try Evinrude XD50 oil and see how it works. It will probably surprise you how little smoke occurs and how clean the combustion chamber will be.

Buoy
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Location: Long Island

Re: Gas Oil Ratio for Evinrude 88 Special

Postby Buoy » Wed Sep 06, 2017 2:17 pm

Thanks guys. I have a new gallon of West Marine TCW-3 oil I'll use up and then try the XD50.

I just acquired this 1985 17' Super Sport with the 1993 88 Special and know little about the history. I do know that the engine starts up with a few clicks and the acceleration from a standing start and performance are excellent. I need to install a tachometer and GNSS receiver, and can then report some performance numbers.

Do you recommend I add anything to the fuel to address the potential carbon build up on this 24-year-old engine?

Thanks again.

jimh
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Re: Gas Oil Ratio for Evinrude 88 Special

Postby jimh » Sun Sep 10, 2017 8:15 am

Evinrude offers several fuel additive products. For general use they have their 2+4 FUEL CONDITIONER. And a product called CARBON GUARD to reduce carbon deposits. See

http://shop.evinrude.com/products/343711/Fuel_Additives

There is also FUEL SYSTEM CLEANER, a product to be used occasionally as a maintenance procedure. See
http://shop.evinrude.com/product/356813 ... ms_Cleaner

Yamaha has a product called RING FREE that they recommend for their engines to reduce carbon deposits.

Mercury has similar products. I wrote about them in detail in an article I published in 2011, when all the products were re-branded. See

Mercury Fuel Treatments: A QUICK Look
http://continuouswave.com/ubb/Forum4/HTML/007434.html

Some sources recommend very aggressive shock treatment of older engines by running them of fuel mixtures with extremely high additive content. I take those recommendations with some skepticism. Older engines with older fuel system components need to be given gentle care in my opinion. I wouldn't pour a quart of naphthalene into a gallon of gasoline and try to run them, as is often suggested.

With today's ethanol-gasoline blended fuels, the fuel itself is quite good at cleaning the fuel system--sometimes too good as older rubber components are often not tolerant of ethanol-gasoline fuel blends.

jimh
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Re: Gas Oil Ratio for Evinrude 88 Special

Postby jimh » Sun Sep 10, 2017 10:07 am

To help older engines--or newer ones, too--to run better when operating at idle, the engine should always be level or have a slight positive trim, that is, a bit of trim out. This helps the oil recirculation system of the engines because gravity helps any extra oil in the cylinders flow into the recirculation system. For more about this and other factors to improve the running characteristics of older OMC two-stroke-power-cycle engines, see

OMC V6 Two Stroke: Some Suggestions for Better Running
http://continuouswave.com/ubb/Forum4/HTML/003888.html