50:1 but runs better with less oil....1977 evinrude 70hp

[roonie]

I was having some issues with this engine with stalling at low idle etc. I then decided to try lowering the mixing ration of the oil and low and behold, she runs much better and does not bog out of the hole. Also does not stall while at idle. I have the correct plugs installed and gapped properly.Carbs just rebuilt.
My question is....will this hurt my engine in the longrun if ive been told to mix it at 50:1? Do all marine engines have a sweet spot of their own when it comes to fuel/oil mixture?

 

[jbjennings]

Re: 50:1 but runs better with less oil....1977 evinrude 70hp

My opinion is that you need to clean your carbs, not lower the oil ratio. If you do, it will shorten the life of your engine.
The most probable reason it idles better is because the lower oil ratio makes the fluid flow faster through the orifices, providing more fuel at idle. The orifices are smaller than they should be, which the faster flow rate helps give the correct amount of fuel due to the lower oil ratio. The orifices are smaller because they are dirty or have a layer of varnish on them. Just curious------how low of a ratio are you talking about?????
Just a guess,
JBJ

 

[boobie]

Re: 50:1 but runs better with less oil....1977 evinrude 70hp

Oil is cheap, powerheads are not. I agree with the above.

 

[clemsonfor]

Re: 50:1 but runs better with less oil....1977 evinrude 70hp

They desinged it to run at a certain ratio for a reason. At one point they did recoment 100:1 on some motors, that has now been superceeded to 50:1 again. Go richer with oil not leaner!

 

[Pecenje]

Re: 50:1 but runs better with less oil....1977 evinrude 70hp

Oil is cheap, powerheads are not. I agree with the above.

Ditto, changing plugs is cheaper then changing powerheads...

 

[1946Zephyr]

Re: 50:1 but runs better with less oil....1977 evinrude 70hp

They desinged it to run at a certain ratio for a reason. At one point they did recoment 100:1 on some motors, that has now been superceeded to 50:1 again. Go richer with oil not leaner!

This didn't happen till the mid 80's and those motors were all recalled for new or rebuilt powerheads. Yes, of course your motor will run better with less oil to degrade your octain level. If you ran it with straight gas with no oil, it'll run better yet.......for about 3 minutes..........Ooops. My motor is stuck. Darn......

One thing you might check, is make sure the right sized jets are in that carb. You never know, the P/O could have changed them.

Run a hotter plug to get better performance.