Evinrude fuel/oil ratio

[Lubosleftboot]

Hi Guys

I have just winterizedmy Evinrude 5hp motor and as I changed the plugs I noticed they were black and oily.Now this is usually a sign of an over rich fuel mixture but I noticed this wee label on the port side of the motor that says 100/1

I have been using a 50/1 ratio as I thought all OMC motors used this ratio

I therefore would like to know if my 1987 5hp rude is meant to run at 50/1 or 100/1 as this would cause plug fouling if the oil mix is to rich if my logic is correct.

LLB

 

[tashasdaddy]

Re: Evinrude fuel/oil ratio

they resended to 100:1 years ago. 50:1 is correct. service directive said to peel the label off.

 

[Lubosleftboot]

Re: Evinrude fuel/oil ratio

they resended to 100:1 years ago. 50:1 is correct. service directive said to peel the label off.

Thanks Tashasdaddy I will rebuild the carb over the winter and remove the offending label..

 

[laredoggg]

Re: Evinrude fuel/oil ratio

hello, i just read your qoute. my older 30 hp evinrude also says 100;1, which i have been running for 2 years with no problems. it even blows some smoke. i will check the plugs over the weekend. what would you suggest i do ! ? thanks ~ laredoggg

they resended to 100:1 years ago. 50:1 is correct. service directive said to peel the label off.

 

[bgbass.1]

Re: Evinrude fuel/oil ratio

use 50:1 have seen what can happen to pistons running 100:1 burns a hole in them

 

[iwombat]

Re: Evinrude fuel/oil ratio

100:1 was fine for good compression, tight tolerances, low wear, fresh water pump, good cooling and moderate usage. Stray out of that envelope and it needs more lubrication to stay healthy. That's the reason for going back to 50:1. If you've been running 100:1 and it still runs right, I wouldn't fret about it. But, I sure would be changing to 50:1 with the next tank and peeling off that sticker.

 

[1730V]

Re: Evinrude fuel/oil ratio

The reason for rescinding the 100:1 ratio was that OMC, among others, found that 100:1 did not leave enough residue on shiny internal parts to hasten corrosion.

They'll run fine on 100:1 but you risk corrosion on internal parts while idle.

 

[gecline]

Re: Evinrude fuel/oil ratio

I have just bought a boat that has a Fastwin outboard, with a number on the engine: 806160 (Can't find any other numbers). I am trying to figure out the fuel/oil ration - is it 24:1 (pre 1964) or 50:1 (post 1964). If there is no way to determine the age of the engine - which fuel ratio is the safest to use?

 

[gecline]

Re: Evinrude fuel/oil ratio

Forgot ot add that it is a Fastwin 18 - 18HP I guess.

 

[1730V]

Re: Evinrude fuel/oil ratio

gecline,

There are several sites that can help you detrmine year. See the link below for the iboats FAQ's section regarding your question.

http://forums.iboats.com/showthread.php?t=158074

If your engine is a '63' or older. Stay with 24:1 using a good TCW-3 oil.