OMC 100:1 mix ratio retract to 50:1 question

[pecheux]

Good day, At one time, and I dont remember which year, OMC recommended 100:1 mix ratio in their OB,s only to retract to the well knowned 50:1 ratio some time later. I know a few other outboard companies had also recommended the lean mix. Some sticked to it ...other retracted. My question is this: Was Chrysler/Force among those who went along with the lean 100:1 ratio only to retract later ? Tx

 

[Frank Acampora]

Re: OMC 100:1 mix ratio retract to 50:1 question

No! Being a reputable manufacturer with good engineering practices and a quality product, unlike the other big names, Chrysler/Force NEVER recommended 100-1

 

[jeff_smith_0423]

Re: OMC 100:1 mix ratio retract to 50:1 question

Ha! That's a loaded response there, Frank

In other news, the remaining Yamaha portables being sold today are recommended to run 100:1 in most conditions.

 

[pecheux]

Re: OMC 100:1 mix ratio retract to 50:1 question

No! Being a reputable manufacturer with good engineering practices and a quality product, unlike the other big names, Chrysler/Force NEVER recommended 100-1

Thank you Frank. Now we all know you are an unconditional Chrysler/Force lover ... lol In my case I tend to favor the underdog of OB's . I once read Force OB's were considered as old fashion not up to date engineering ... humm dont all those 2 strokes basicaly operate in the same manner and built practicaly the same ?
I know this is going to raise eyebrows ... LOL

 

[jeff_smith_0423]

Re: OMC 100:1 mix ratio retract to 50:1 question

Frank's the resident Chrysler/Force expert but really, the reputation for Force didn't go downhill until Chrysler was forced to divest and sold to U.S. Marine. After that, it seems as if the outboard line was an afterthought. Great to have in the corporate stable but not anything deserving of time or engineering money. They never released a V6 engine so they had no presesnce on the professional fishing circuit. Mercury only did cursory updates to the line while Brunswick figured out how to phase it out. I was just flipping through a Popular Mechanics article on Google books that touted Chrysler's 55hp twin as having the best power to weight ratio in the world. All in all, it was a good line of products that didn't get the corporate attention it needed and was eventually the casualty of market conditions - and unfortunately it just deteriorated to what we all read about now.

 

[pecheux]

Re: OMC 100:1 mix ratio retract to 50:1 question

Jeff, Tx for your feedback.
There is a descent history of Chrysler OB's in my family as my father (indirectly me lol) owned a 90 hp Chrysler which I loooved ... something about the sound of the motor that was unique. then I eventaly owned a 6 hp ... now own a 1997 15 hp Force. (owned all brands in betwen) Only difference I see is that in opposition to the 6 hp Chrysler .. this one always starts on 1st or 2nd pull so I presume Merc did something right with the electronics.

 

[coolguy147]

Re: OMC 100:1 mix ratio retract to 50:1 question

chrystler even though they went out of business. i kinda liked them. simple yet they worked good. still an omc fan number 1 mercury tohatsu suzuki yamaha last. chrysteler with mercury up in there

 

[Frank Acampora]

Re: OMC 100:1 mix ratio retract to 50:1 question

The thing about Chrysler was that they bought West Bend which had already been owned under a different name--I just heard it recently but, of course, forgot it. So the design is probably 60 years old or more. (Chrysler bought them in 64 so do the math.)

The basic design is OLD no doubt about it. It is the simplest crossflow design you can make. As such, It will not produce the same power from the same cubic inch displacement as more modern designs and really can not be upgraded too much. Port work will boost horsepower some, but in the end, you still have an underdog. The two exceptions would be the
1. Racing 135 and 150 with water cooled and tuned exhaust stacks and
2. The (late Chrysler) designed twin carb 55, 60, and 65 series two cylinder engines. Had Chrysler not nearly gone bankrupt and had they been able to extend this design to their larger engines, you would still see Chrysler outboards, and they would most probably run rings around OMC and Mercury.

The old design 55 weighed 156 pounds--the lightest 55 ever on the market and even though simple in design my 1967 model would outrun the three cylinder 55 Evinrudes of that era.

My admiration for the three engines actually designed by Chrysler is great. These engines had TREMENDOUS low end torque--to the point where if under-propped, they would strip out lower unit gears on a hole shot. Top end wasn't too shabby either.

For the late 70s and early 80s (last was made in 84) they were cutting edge design in crossflow engines--large bore, massive crankshaft, packed block, long beefy rods, large bearings, BIG ports, equal length and separate exhaust runners for each cylinder, through (piston skirt) induction and large venturi area. Chrysler engineers really did their homework on these engines.

I only wish That it were at all possible to modify some of the components to fit the 3 and 4 cylinder engines--well, it is possible, but it would take cubic money and more time than I have available.

I just sold my 55 for a song, but my 60 has other plans. It is eventually destined to be mounted on my 1971 15 foot Glastron and I expect that because of its reduced weight, it will outperform the Chrysler 90 that is on there now.

 

[coolguy147]

Re: OMC 100:1 mix ratio retract to 50:1 question

well all the videos ive seen on youtube there good. loud one of them.


156 pounds! my 35hp johnson is about 140 pounds!

werent kidding

 

[pecheux]

Re: OMC 100:1 mix ratio retract to 50:1 question

For my knowlege base (or lack of it) would it be then ok to presume that outboard motors from these companies would have a normal tolerance in lubrification that could be anywhere from 50:1 to 75:1 ? I personaly find it to be a BIG drop from motors that are so-called built to use a 100:1 mix to retract to half (50:1) of what they claimed from the begining. In this type of situation I would have a natural tendency to think the in between ratio of 75:1 would have been more credible ...

 

[Cricket Too]

Re: OMC 100:1 mix ratio retract to 50:1 question

The "drop" to 50:1 was only because the manufacturers realized that the 100:1 mixture wasn't leaving enough of a film on engine internals to protect them from corrosion while the engine was not in use.

They dropped back to 50:1, solely to protect the engine from corrosion, not to protect it when running.

 

[pecheux]

Re: OMC 100:1 mix ratio retract to 50:1 question

The "drop" to 50:1 was only because the manufacturers realized that the 100:1 mixture wasn't leaving enough of a film on engine internals to protect them from corrosion while the engine was not in use.

They dropped back to 50:1, solely to protect the engine from corrosion, not to protect it when running.

Then in theory any OB that is being used weekly or bi-weekly could run safe with a leaner mix than 50:1 ... maybe not at 100:1 but somewhere in between ... but obviously nobody buys that ... since manufacturer wont back it up.

 

[Cricket Too]

Re: OMC 100:1 mix ratio retract to 50:1 question

Well the old VRO pumps used to run anywhere from 100:1-150:1 at idle and then would richen up to 50:1 as load increased.

In 1993 when OMC changed them over and called them OMS(Oil Metering System) pumps, the ratio didn't vary near as much or barely at all. It averages about 60:1, slightly leaner at idle and slightly richer at full throttle.

So obviously they can at least idle with the leaner mixture, but even when VRO was around, OMC had them running 50:1 at speed. I don't know if I'd run one at higher RPM on 100:1.

The E-tec's can run a lean oil mixture, but they have to be running the XD 100 full synthetic to do it, and the ECU's have to be programmed a certain way to make them run that lean mixture.

 

[jeff_smith_0423]

Re: OMC 100:1 mix ratio retract to 50:1 question

So obviously they can at least idle with the leaner mixture, but even when VRO was around, OMC had them running 50:1 at speed.

I can't find it right at this moment but there is a thread that discusses some OMC engineering tests that one of the members was involved in back in the late 70's or early 80's. Once the internals are lubricated with 50:1 mix, they can run at IDLE with no oil for quite a while. The tests were actually stopped after a period of time because their initial objective was proved. After that, the OMC owners manuals for a time indicated that one could power a boat back to the ramp at speeds less than 1100 or 1200 RPM with no oil in the event of a runout.

 

[Cricket Too]

Re: OMC 100:1 mix ratio retract to 50:1 question

Hmm, that's pretty interesting. Thanks Jeff, didn't know that.

I guess that goes to show how long a 50:1 mixture will "stick" to things once they are coated.

 

[Frank Acampora]

Re: OMC 100:1 mix ratio retract to 50:1 question

Remember that ALL internal bearings in a two cycle outboard engine are ball and roller. In industrial use other than outboards, these bearings are commonly run without an oil bath. In the case of sheilded bearings, the initial charge of oil from the factory is the only lubrication they get for life. SO: A fresh charge of oil with each revolution in an engine is actually better lubrication than they need.

The quote I read right here on an iboats forum was that OMC said that after break in, an outboard could be run at 2000 RPM or less all day. (Not exact wording). That is difficult to believe, but remember that even gasoline has SOME lubricating properties; the fuel pump in your auto is immersed in it and has no oil in it at all.

Also, think about your wheel bearings--a light film of grease usually lubricates them for the life of the vehicle unless (on a trailer) the grease is contaminated or washed out with water.

 

[Cricket Too]

Re: OMC 100:1 mix ratio retract to 50:1 question

Good point Frank. Makes me think about wheel bearings in a skateboard wheel, or roller blade wheels. They get a small amount of lube at the factory and are then good for a long time.

Is that what you meant by shielded bearings?

 

[russellmead10]

Re: OMC 100:1 mix ratio retract to 50:1 question

The owners manual I read a while back (yeah, had one and could even read) stated that the 100:1 was recommended when OMC found their "newer" bearings (this was with an '87 15hp Johnson) were sufficiently lubed with the 100:1 ratio. However, a later technical bulletin recommended reverting to 50:1 because the 100:1 ratio starved the cylinders of lubrication at higher engine speeds and loads, causing accelerated piston/ring/cylinder wall wear.

My general practice;
I run 40:1 to 50:1 for general use (more oil first tank of season or higher temp/heavier boat load)
75:1 if primarily trolling & low speed
100:1 if basically entirely trolling my skiff for endless hours (reduces plug fouling)
40:1 to 25:1 with extended Wot running, like 50-100mile endurance runs between 3/4-Wot except for fuel stops (also change to non-gapable high speed spark plugs (like common in many of my other small merc's)). Not sure how many 100's hours I've put on the Johnson 15, but it still starts every time and pumps out plenty of power.

 

[jeff_smith_0423]

Re: OMC 100:1 mix ratio retract to 50:1 question

Seems like a lot of extra work and fuel tanks laying around for what must be meager performance gains. I'll stick to 50:1 and keep a spare set of plugs in the boat.

 

[pecheux]

Re: OMC 100:1 mix ratio retract to 50:1 question

As stated on another board, one of my OB's a 6 hp Johnson is shared and gas tank is also shared. Twice already some guests did the wrong mix. One time it ended up being at 150:1 ... and fortunatly was ran that way idling with a few short wot bursts. Ran ok but it was noisy ... had that back to 50:1 on the spot. Another time it was mixed at 100:1 and ran real well under wot for one hour or so. then I got it back to 50:1 ... lol but I did notice is that the engine ran rougher at idle with the normal mix. Base on conversation with retired my OB mecanic it would appear OB manufacturers are going wayyyy safe with their 50:1 mix recommendation.