77 Evinrude 15hp

[Dhow]

I am having trouble getting the gas/oil ratio just right. I am going through spark plugs like crazy. Is there some kind of meter I can buy that takes a sample of the mix and tells you the ratio?

[overdalimit]

How much oil to gas are you mixing? I would run that motor at about 50:1 with a good TCW3 2 stroke premix oil. This would be about 16 oz oil to 6 gal gas. I would think that your problem is most likely a carb or compression issue. Start by checking the compression it should be the same on both cylinders and around 110 - 115. If it is below 90 you have problems. check back and we can give more things to try.

[boatfixer]

To answer your question about finding out what ratio of a particular sample, a long time ago they used to make cards will rings on them and you would put a determined amount of mix on it, wait for the gas to evaporate and see how far out the oil stain was and it would at least put you in the ball park. I havnt seen one for about 20 years though. A small engine shop may or may not have them. Don't be suprised if you get a strange look. We had them at a Vo-Tech when I was there.

In the mean time follow overdalimits suggetions and make sure you are using the correct plugs.

[marine_man]

I'd try one pint to six gallons (which is the same as overdalimit's reccomendation)

marine_man

[stoneroller]

I have a 77 70HP Evinrude And This opening day I went to Amsoil marine 100 to 1 and all ready in just to tanks of gas I see alot less smoking and low speed idle has greatly inproved,that is 8oz to 6 gals.