ratio for OLD johnson 10hp outboard?

[Gypsy]

I just picked up a 14' fiberglass boat to do marina duty from my Houseboat. It has an old two cyl Johnson Sea Horse 10 hp motor. It has been painted with a brush so I cant find any #s.
Judging by the engine cover style I'm guessing it's early 70's. Looks like a robot with tail fins. It runs great and starts on the 2nd pull.
I mixed a tank at 8 oz to 5 gallons and it seems to run okay but smokes more than I think it should and when I ran it in a barrel there was more oil in the water than I would like to see.
Any help is appreciated.

 

[blano]

50:1

 

[Gypsy]

Thank You.

 

[Jelly]

Use 32-50:1.

While I realize this isn't exactly a new, state-of-the-art engine, I must recommend to you that you try out a synthetic two-stroke lube.

I gave Mobil MX2T a try a while back (in my non-marine applications) and from now on will ONLY use this!

While I use a mineral based engine lube in my old truck, I believe synthetics are the way to go in two-stroke applications...

[ July 16, 2004, 07:35 PM: Message edited by: Jelly ]

 

[BUBBA0420]

That early 70's Johnson is probably an early 60's
Johnson or maybe 50's going by your description
back then they used a 25:1 ratio currently you are mixing at about 24:1 by the 8oz's per 5 gallons. With today's new oils you can lean it
to about 32:1 and cut down on the smoke. I wouldn't go as far as 50:1 however on an older engine like that

 

[blano]

quote:

---

you are mixing at about 24:1 by the 8oz's per 5 gallons.

---

What? He's actually mixing it at a ratio greater than 50:1 as 50:1 is equal to 2.6 0z per gallon or 13 oz for five gallons. 24:1 would be about 26 oz for 5 gallons and 75:1 would be about 6.5 oz for 5 gallons. So in reality he us using a ratio somewhere in between 50 and 75:1.

 

[Bio-T]

I wish I could post this chart for marine 2 cycle mixtures and non-marine mixtures permanently on this site. But this link will work, and then put it in your Favorites for futureuse: http://www.csgnetwork.com/marineoilfuelcalc.html/:


Also scroll down toward the bottom, it has a calculator for almost everything you would want to know.

 

[Gypsy]

OOPS I meant 16 oz per 5 gallons. One small bottle.
I used Pennzoil for the first tank. I picked up some Castrol to use from now on.
I guess I'll try 16oz to 6 gallons.

 

[DJ]

The early 70s stuff looks pretty much like the 80s stuff, from your description I would say it is older like 50s-60s as Bubba said. I found a great boat/motor forum http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=forum;f=28 After doing some reading there and asking a few questions I can say the 6hp Johnson I got is a '71. I bought the manual and a bunch of tuneup parts and now it even runs.

As for the smoke, in a barrel they smoke bad and yes it looks like a lot of oil but is normal. If your motor is older then you likely do need a richer oil mix. I am trying the Pennzoil synthetic TCW3 and like it sofar.

 

[Gypsy]

It is a 1957. Is the 50:1 still good?
I've heard that these old motors need more oil.

 

[Drstressor]

I had a '55 Evinrude when I was a kid. It took non-detergent automotive oil at a 24:1 ratio. They sold special outboard oil that was to be used at the same ratio, but hardly anyone used the stuff. I switched over to 50:1 when TCWC oils became available. The engine lasted into the late 1970s before the head cracked. Never had a lubrication related problem.

 

[Ugly3]

A 1957 10 hp outboard would call for a 24:1 mixture. That is a quart of oil to 6 gallons of gas. They smoke more than a little but they run forever.

 

[UncleS2]

We had one of those old green 10 HP Johnsons with the rounded cowl & "tailfins". Definitely from the 1950's, Dad bought ours around 1970, along with a Duracraft 14 ft semi-V. Ran great for years.

Mixture? As I recall, we used a quart of oil in a standard 6-gallon steel outboard tank.

 

[Cujet]

keep in mind that the spec for many of those old 1950's engines was to use 30wt motor oil as the premix.

Todays 2 stroke oils are far better than standard 30wt of years ago.

As I have mentioned in other posts, using todays quality oils this is a good guideline.

32 to 1 will provide enough lubrication for nearly any application, short of some very specific and unusual applications. It is even enough for top factory level endurance racing motorcycles such as the 500cc 200+HP GP roadrace bikes. It is enough oil for proper lubrication for the most highly loaded 2 stroke engines commonly available, 85 and 125cc motocross bikes.

50 to 1 is enough oil for low stress applications such as outboard engines, ultralight aircraft engines, snomobile and personal watercraft engines.

When I say low stress, I am talking about specific output per cc or ci. Engines that make 1HP per 5cc or less displacement are high stress engines.

Chris

 

[JohnnyG]

My 1953 (6.5 hp, twin cyl.)calls for 16:1, the original label is still on it. Thinking like many have said, that modern oil is so much better, that I could go to about 50:1 did not work out. It was not engine damage or anything like that, the carb, crudely designed as it was, would backfire seriously at the higher ratios, particularly at idle. I ended up abut 25 or 30:1 and the thing runs great.

 

[1 FMF]

from experience, the the older the motor the higher the oil/gas ratio mix. Trick is determining the year of the motor.
I'd try starting out around 30:1, with only a gallon gas in tank, with today's OMC or Merc/Quicksilver 2-stroke oil. If you see wet plugs or it runs/idles bad then lean it out more, or try running a hotter plug. The 2-cycle oils today definitely throw off what was required pre 1980, along with the specified spark plugs vs. today's plugs #'s.

I've read some articles, mostly from marine industry and maybe biased but I believe them, is that "their" 2-stroke oils are better than the automotive brands because they can run leaner mix ratios without ring problems and in general without idle fouling problems. This is aside from the synthetic 2-stokes like mobil or amsoil, which I think are equal to or better than the OMC or Merc oils, for what it's worth.

If the 10hp johnoson doesn't work out, I have a nice 70's 18hp evinrunde I can't run on my achilles raft anymore (rated 10hp max and broken floorboard stringers). Should stand you boat up in the air nice

 

[BUBBA0420]

Gypsy: I wouldn't go beyond 32:1 Old motors used
needle bearings on the crank and rods and they
require oil. Also use a good TCW-3 Oil for the engine with 89 octane gas and that baby will run
forever

 

[Cujet]

Once again, I must mention that two stroke bottom ends nearly all have needle bearings and are well lubrucated with any reasonable oil ratio. That is because some of the oil does not stay mixed with the gas once inside the crankcase of a 2 stroke. What can only be described as a migrating flow of raw oil forms on the lower end components such as the crankshaft big end bearing, the con rod and the crankshaft bearings. This is simply the nature of nearly all 2 stroke engines. 24 to 1 will not provide any more available lubricant (in general practice) to the bottom end than 50 to 1. What tends to occur is that piston and ring life are slightly shorter with lean oil ratio's combined with very high RPM. This is well outside the scope of normal outboard operation.

50 to 1 will provide all the lubrication your outboard can use.

One thing to keep in mind that was discussed and hinted at by JohnnyG's post is that high oil levels may achieve other results not related to lubrication. Such as air to fuel ratio changes. Also worn out reed valve sealing may be improved by high levels of oil. As will worn out ring sealing.

Simply put, a clapped out 2 stroke will do better with high levels of oil.

Chris

 

[srivett]

We always used 20:1 in our old Johnsons as well as our 1970 Ski-Doo. One sea horse was from the 50s and another was from the 70s. The green ones are older than the old white ones.

20:1 did not foul the plugs either, they would always start on the first or second pull at the beginning of each season. My dad is the orgional owner of the 50s Sea Horse and it's only been rebuilt once. It doesn't live in the water but it has seen a fair bit of use.

Steve

 

[Repecat]

Older Johnsons (pre-1950) of small displacement generally take 1/2 pint per gallon of fuel. Some of the larger displacement engines of about 16 BHP take one pint per gallon. The recommended weight was 40, not 30. Basically the same for Evinrude. Merc recomeded the same ratio, but 30 weight. I have a 1925 Johnson that uses a 12:1 ratio with minimum smoke.