50-1 and 90-1

[fishingjim66]

I had a old merc 65, with 50-1 ratio, it would burn very rich while I was trolling. My mechanic told me to try 90-1 while trolling and 50-1 when I was running fast, I had 2 six gal. tanks so it worked great.. Can I do the same with a 1975 55hp evinrude?......... Thanks fishingjim66

 

[JB]

Re: 50-1 and 90-1

You can do whatever you want, Jim. I do not agree with your wrench and am not surprised that you don't have the Merc any more. Do that to the 'Rude and you probably won't have that one anymore either.

 

[1946Zephyr]

Re: 50-1 and 90-1

LOL JB. You definately make a good point.

Anyone who says that outboards can run on less than 50:1, must have had a few Martini's on their lunch break. If your old Merc ran rich while trolling, it was likely because (a) the low speed jets were set too rich, (b) your igntion system was not running correctly, or hot enough. Possibly the incorrect plugs or (c) You could have possibly had a float level issue.
In the mid '80's, OMC built outboards that were "100:1 motors" and they ended up paying dearly for that blunder. Many outboard owners had fresh rebuilds, at OMC's expense. I benefitted from this blunder, when a friend of mine gave me a beautiful 1986 Evinrude 25 with about 10 hours on a freshly rebuilt powerhead. I turned around and sold it for $800........well, that's another story.

 

[Blazinmonkey]

Re: 50-1 and 90-1

``An OMC VRO motor mixes the oil at anywhere from 50:1 to 150:1.

The only time it would really be mixed at 50:1 would be during wide open throttle. If you were putzing along, idling and cruising then it was probably closer to 100:1''

``As the throttle opening increases, the stronger crankcase pulses cause greater piston travel resulting in longer oil pump strokes. That means, more oil is delivered increasing the amount of lubricant in the fuel up to a 50:1 ratio.''


is this not true?

 

[Johny25]

Re: 50-1 and 90-1

Don't believe that is correct^ At idle there would be less FUEL flowing also, matching the oil output. As RPM increase then both should increase respectively.

As to the OP, I have run 65:1 before when trolling for long periods on my small Johnsons outboards before hoping for a better idle but the difference is virtually unnoticeable and not worth the extra wear on your internals IMO. But I would never run 90:1

Stick with 50:1, if your motor is running proper then you shouldn't have a problem at 50:1

 

[Joe Reeves]

Re: 50-1 and 90-1

I had a old merc 65, with 50-1 ratio, it would burn very rich while I was trolling. My mechanic told me to try 90-1 while trolling and 50-1 when I was running fast, I had 2 six gal. tanks so it worked great.. Can I do the same with a 1975 55hp evinrude?......... Thanks fishingjim66

As long as you have a signed Notarized statement from that mechanic which promises to rebuild that 55hp Evinrude free of charge if it seizes with that mixture... do it.

 

[fishingjim66]

Re: 50-1 and 90-1

As long as you have a signed Notarized statement from that mechanic which promises to rebuild that 55hp Evinrude free of charge if it seizes with that mixture... do it.

This is Fishingjim66 again. I had a 1960 Dorsett cutty 16ft that had the 65 Merc on it. The boat was always garaged, I am very careful with all my boats, the Dorsett was my favorite . The mechanic ran a small Merc autherized shop in Stockton Ca. I ran the boat and motor for 21 years always being carfull about oil mix, I retired the boat and motor due to a bad reed valve. I sure did not intend to step on anyones toes, but It worked for me for alot of years primarily trolling for Trout.
I will promise 50-1 for Rude...Thanks for the lively talk.. fishingjim66

 

[Joe Reeves]

Re: 50-1 and 90-1

No problem on my end... no damaged toes. I also had a Dorsett back in 1961/62, a 17' fiberglass cabin job that would do 36 mph with a 1961 Evinrude V4 75hp and later also 36mph a 1962 Johnson V4 75hp. I still have pictures of it with my late wife sitting on top of the cabin..... and I miss them both.

 

[Jlawsen]

Re: 50-1 and 90-1

Can't speak for the JohnnyRudes but Mercs typically run about 65-70:1 at idle and then fatten up to 50:1. You can run the test yourself by premixing a fuel source and then testing the output of the oil pump at idle.. You might be in for a suprise if you think 50:1 is the only possible mix.

 

[Blazinmonkey]

Re: 50-1 and 90-1

``Don't believe that is correct^ At idle there would be less FUEL flowing also, matching the oil output. As RPM increase then both should increase respectively. ''

JOHNY25... VRO- Variable-Ratio Oiling....
see link http://continuouswave.com/whaler/reference/VRO.html

it is correct... believe it or not...

 

[kenmyfam]

Re: 50-1 and 90-1

If you are pre-mixing then it's 50 to 1 for me !!!!

 

[1946Zephyr]

Re: 50-1 and 90-1

Oil is the cheapest thing you'll ever put in an outboard. Why skimp on it?

 

[JB]

Re: 50-1 and 90-1

``Don't believe that is correct^ At idle there would be less FUEL flowing also, matching the oil output. As RPM increase then both should increase respectively. ''

JOHNY25... VRO- Variable-Ratio Oiling....
see link http://continuouswave.com/whaler/reference/VRO.html

it is correct... believe it or not...

The intent and the claim are correct. That is why the original VRO was a disaster and destroyed so many JohnnyRudes.

 

[the machinist]

Re: 50-1 and 90-1

I have ran many of my 9.9hp TROLLING motors using 100-1, but used FULL SYNTHETIC oil. But I would NEVER run a larger OMC on that lean a oil mix. My 70hp gets 50-1.

 

[Johny25]

Re: 50-1 and 90-1

The intent and the claim are correct. That is why the original VRO was a disaster and destroyed so many JohnnyRudes.

See you learn something new everyday : ) I guess my common sense thinking on how it SHOULD operate was totally wrong :redface:

 

[JB]

Re: 50-1 and 90-1

No, Johnny. Your reasoning was excellent. That is how they intended it to work. It just didn't do what they expected. When they replaced it with the OIS system (also called VRO2) that worked fine, but did not oil at a 150:1 rate at low rpm.

That error was made by the same guys who thought that the smaller engines would do fine at 100:1. The problem was that as soon as it worked in theory they made it without complete development. Pecursors to OMC's demise.