Fuel/Oil ratios in 1964?

[MI_Roger]

I am guessing engines built during the early 1960's were designed for a 32:1 ratio, or 4 ounces of oil for one gallon of gas.

This is for a 1964, 850cc, water-cooled, DKW 3-cylinder, used in automotive applications, and subsequently tweaked for better performance/racing use.

No owner's manual with a 55+ year old racing engine. What is a safe assumed oil ratio?

Thanks,

 

[Chris142]

Does it use roller bearings or plain bearings? My 1984 Honda ATC250RI bought new required 20:1. Back then most of the Japanese bikes recommended that ratio. If it has plain bearings those usually got 16:1.

 

[The motor guy]

Are ratios based on engine design or is it the improved quality of the oil? Or is it just the EPA saying you can't do that?

 

[Chris142]

Originally Posted by motor_oil_madman
Are ratios based on engine design or is it the improved quality of the oil? Or is it just the EPA saying you can't do that?

The old engines with Plain bearings require a lot of oil. The ones with roller bearings can use 40:1,50:1 etc even 100:1 per Amsoil if the oil is very high quality and the jetting is perfect. I tend to stay with 40:1 myself.

 

[patfan]

here is a YouTube video https://youtu.be/y1VTKDX-A14

 

[doitmyself]

This should be a fun research project for the O.P.. My initial search without much investigation showed 25:1 and 40:1 ratios: https://www.google.com/search?q=DKW...BcQ8NMDegQICxA-&biw=1920&bih=944

Back then, the oils were mineral oils with very few additives. How does a person figure out what to use with today's 2 cycle oils packed with additives and used at much lower amounts?? My 1970's Homelite saws ran at 16:1 back then. Besides lubricating, the oil portion also assists with ring seal, etc..

There's also that strange concept that at very high oil concentrations, i.e. 16:1, the gasoline portion is actually running leaner through the engine because of the oil displacement. It's counter-intuitive to the idea that more oil = richer.

 

[racin4ds]

I have read and researched on studies where they have found all the way down to 10:1 ratios provided the most power due to improved ring seal. Extra oil in any two stroke definitely doesn't hurt anything and at worst it will only foul the plug. In my opinion, the extreme ratios (50:1 and up) are only due to EPA and emissions requirements.

 

[ripcord]

Have you seen this? http://www.dkw.co.za/technical_information.html#Engine Lubrication
Also, this: http://www.carsandracingstuff.com/library/articles/22150.php

According to the first article, starting in the early sixties they added an automatic oiling system. Cold weather caused issues so later they added an oil heater and a pre-mixing chamber. Also, they had greased and sealed ball bearings for the crank starting in the sixties.

The second article infers that before the automatic oiler, the premix ratio was 40:1, which often lead to fouled plugs.

 

[Cujet]

The video shows bushings on the con rods, verified by the link. The link also suggests that for performance applications, needle bearings are used, as bushings are risky.

No idea what bearings or bushings your engine has inside.

However, it's good to understand the viscosity of the oil does much of the lubrication in a two stroke. Additives in modern two stroke oils do not render them twice as good with regard to lubrication. In fact, straight 30 viscosity oil was the standard for many, many years and provided good engine life.

To eliminate operational issues modern 2 stroke oils use both additives and lubricant blends that address, smoke, ring sticking, carbon buildup, plug fouling and so on. Remember, a stuck ring will ruin an engine due to excessive blowby.

I've posted the following 2 stroke oil test result information, from many years ago. I was involved with outboard engine testing. Don't believe the hype, and use enough of quality oil to protect your engine. In general, a modern high performance 2 stroke will do well on 32 to 1. In our outboard race engine testing, 8 to 1 provided the most power, but was difficult to deal with. 16 to 1 was very close. 32 to 1 provided all the wear protection possible, and any ratio above 32 to 1 resulted in increased wear. 100 to 1 was fine at idle and slow speeds, but not under load, and resulted in less power and much more rapid wear, so much so, we stopped the testing.

40 or even 50 to 1 is generally fine in quality lower output two stroke engines. However, much of this depends on how the engine is made. Some low output engines use bushings (even today you can find super el-cheapo engines made this way) and need a 20 to 1 mix.

 

[Lubener]

Not sure about the sixties but I have an old working 24 inch Homelite chainsaw from 1973 which specifies a 24:1 mix.

 

[Rygrego]

We had a 95hp Mercury on our 1968 ski boat back then and it called for 50:1. We usually ran 40:1 and that engine ran for more than 20 years.

 

[Elkins45]

My Sea King (Montgomery Ward rebadged Gale) 15hp from 1965 is supposed to run at 24:1.

 

[BrocLuno]

I collect old chainsaws and outboards now. I was in the boating industry at an OMC shop in the 1960's. We batted this around with factory reps and the race boat guys. I ran a little J Class outboard in off-shore sometimes.

AND, I owned a DKW sedan

All used 32:1 unless they were plain bearing motors. Even today on Hot Saws I build, still 32:1. I use only JASO rated oils, mostly from Motul.

Back in the day it was Full Bore brand oil only (which came out in Dirt Bike magazine tests as having lowest cyl head temp and clean chambers).

I also helped on 2-stroke race bike efforts for some buds. Mostly Yamaha IT enduro bikes. But I was partial to Spanish bikes (Bultaco & Ossa) and tuned a lot of those for trail riding at altitude (9000 ft + ).

My race bike was a Hodaka 125 ...

So I've seen the inside of more 2-stokes than I care to count.

You don't need to take my word for it, but oil is cheap. Engines are not. That DKW will oil starve on long down hills with the throttle closed - so don't. Your only fix is to run the oil fat and it will carry you through slowing with the throttle off and down hills. If the down hill is more than a 1/4 mile, put in neutral and rev the engine a few times while using the brakes to control speed, then let it idle while costing along in neutral. Managing a 2-stroke is different than a "normal" car.

Modern 2-strokes with direct injection at the bearings are a world away from from 1960's technology. Back then the Saab's and DKW's (and Auto-Unions) were mostly round town cars for most folks. Or farm to market cars. They seldom saw more than 45 MPH, and a trip of 30 miles was a fair distance. Sure, they will go to Colorado, but only if cared for. Buy good oil and mix it at least 32:1 and kill some mosquitoes

Plus you get to sneer at the EPA and planet warmers as you whizz by

Full Bore is long gone, and so are many other good 2-stroke oils. Do your research: https://www.oilspecifications.org/iso_2t.php There are good USA made oils, but mostly it's a Euro and Japan thing. Buy in bulk and remember you are dealing with not only oil, but gasoline with ethanol. See what the refiners and blenders you are considering say about their oil for use with ethanol gas ...

 

[CT8]

I run 32 to 1 in all my ope. . I weed wack 3 acres on the side of a hill for fire control with a husky 535 ? lx and there is definitely more power. and the exhaust port is clean.