Oil Injection or NOT

Teammuir1

Seaman Apprentice
Joined
Aug 13, 2010
Messages
45
OK this is what I am wondering....
can a person take off the entire Oil injection system on 2000 70hp Johnson outboard and only add 50:1 oil ratio in the gasoline and the motor retain the same amount of oil as if the injection system was working?
 

d.boat

Chief Petty Officer
Joined
Sep 19, 2008
Messages
520
Re: Oil Injection or NOT

If you use the search function, you'll find this topic is discussed a lot. The short answer is yes. Some of us would say, premixing is more reliable than the oil injection so go for it. Others would say, why would you disconnect an excellent oiling system?

This is an interesting read and I think it's the most objective explanation of the system: continuouswave.com/whaler/reference/​VRO.html

If you decide to disconnect, again use the search function, there's a million discussions on it.
 

54fleetwin

Petty Officer 1st Class
Joined
Aug 1, 2010
Messages
282
Re: Oil Injection or NOT

I am new to outboards so I can not comment specifically on the question.

I am a 2 stroke motorcycle guru and can share some 2 stroke info with you

During the early '70's the big Jap manufactures started fitting the street legal and trail model 2 strokes with oil injection.
The general public was concerned about reliability and 90% of those bikes you find today have had it disconnected,
Fact is the failure rate of the systems were less than 1%.

Once you add oil to the gas you have less fuel passing through carb jets.
Now you should rejet the carb to run properly.
By the same token, if you have an old outboard designed to run a 16:1 mix and you decide to run that new 2 stroke oil designed for 50:1, you will need to alter carb jetting for proper running.

Now if you outboard has fuel injection, I can't help and the information I provided is useless.

I would use the oil injection system if it was me.
 

Teammuir1

Seaman Apprentice
Joined
Aug 13, 2010
Messages
45
Re: Oil Injection or NOT

d.boat : My oiling system has been removed and I was
very concerned with it.. thas why I asked the question.. it was late
last night or early this morning... when I posted.. I thought about the
search engine after I posted this thread I did read and find the answere.
I dont mind mixing.. I have done this since I owned my boat 3 yr ago.
so nothing would change I would rather be safe than sorry... so
I will keep mixing.
Thanks for all your reply's

I know I will have many more questions.. to come...
Ron
 

Teammuir1

Seaman Apprentice
Joined
Aug 13, 2010
Messages
45
Re: Oil Injection or NOT

54fleetwin :

you make alot a great comments.... the fact is my motor had the injection system removed already.... and the original owner stated he
just mixed the fuel 50:1 with oil.

THAT MAKES THE A LOT A SINCE about rejetting the carbs.
you would be right I am now deluting the fuel....and that will make
a difference in how she would run.. or it seems like it would?
I know this with my older 33hp Johnson if I mix the fuel to 30:1 verses
50:1 the motor looses power... I know I have done it.....
so it makes total since in what you are saying... maybe someone else here
on this forum would know the answere for sure....and see if I have to Rejet
Thanks
Ron
 

Teammuir1

Seaman Apprentice
Joined
Aug 13, 2010
Messages
45
Re: Oil Injection or NOT

here are some pictures... so far..
the cover.. which I have not matched up with someone elses on line.
I have a majenta color Pink or something along with the grey...
I do not know if its fuel injected so I post a pic of the carb system.
maybe you guys can tell.

:D
 

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Al-53

Chief Petty Officer
Joined
Jul 17, 2008
Messages
491
Re: Oil Injection or NOT

I don't believe u have to re jet the carbs for mixing....the amount of oil with a 50;1 ratio does not thicken gas to make the flow rate slow any.....

you will be fine with mixing and not needing a re jet...there are a bunch here who have did away with the oil injection and i never seen one say they need to re jet....

Al
 

54fleetwin

Petty Officer 1st Class
Joined
Aug 1, 2010
Messages
282
Re: Oil Injection or NOT

I don't believe u have to re jet the carbs for mixing....the amount of oil with a 50;1 ratio does not thicken gas to make the flow rate slow any.....
its not the thickening of the gas, it is that fact that it changes how much
gas is available.
ex: an engine designed for 16:1 would run rich with fuel at 100:1
So an engine designed to have no mix in the fuel is going to run lean when oil is added.
Your engine, Your choice

you will be fine with mixing and not needing a re jet...there are a bunch here who have did away with the oil injection and i never seen one say they need to re jet....

Al
Just because others have done it doesn't make it right.
Maybe you wont have a problem. My experience with 2 strokes makes me second guess not changing the jetting.

again, Your engine, Your choice

its not the thickening of the gas, it is that fact that it changes how much gas is available.
ex: an engine designed for 16:1 would run rich with fuel at 100:1
So an engine designed to have no mix in the fuel is going to run lean when oil is added.
Your engine, Your choice
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
Re: Oil Injection or NOT

54fleetwin, 1970s 2 cycle Motorcycle Oil injection is quite different that Outboard oil injection. The 2 cycle motorcycles had oil pumped into the air intake stream, via a banjo fitting on the neck of each cylinder, or into the intake manifold. The motorcycle carbs therefore contained only pure gasoline.

All non Direct Injection outboards mix gas and oil, prior to supplying thee carbs or EFI with the mixed fuel. Since the carbs already contain premix, if the oil injection is disconnected, it has no bearing on the carb jetting.
 

54fleetwin

Petty Officer 1st Class
Joined
Aug 1, 2010
Messages
282
Re: Oil Injection or NOT

54fleetwin, 1970s 2 cycle Motorcycle Oil injection is quite different that Outboard oil injection. The 2 cycle motorcycles had oil pumped into the air intake stream, via a banjo fitting on the neck of each cylinder, or into the intake manifold. The motorcycle carbs therefore contained only pure gasoline.

All non Direct Injection outboards mix gas and oil, prior to supplying thee carbs or EFI with the mixed fuel. Since the carbs already contain premix, if the oil injection is disconnected, it has no bearing on the carb jetting.

Thank you for clarifying that.
As I stated from the beginning, I am new to outboards.
I just wanted to through out some food for thought.
My info still applies to radically changing the oil ratio from16:1 to 50:1 or 100:1.
This is something often overlooked by the guy that buys the new fangle 2 stroke mix that hits the market.
 

Teammuir1

Seaman Apprentice
Joined
Aug 13, 2010
Messages
45
Re: Oil Injection or NOT

Chris1956 :

I went over to my shop last night and had my brother and
uncle meet me ... MY brother knows a little more than I do about outboard
motors.... he has been around them longer... I mentioned to him would I
need to re jet the carbs... he stated the very same thing the oil is mixed
with the gas before entering the carbs....
So I understand this now.... and I will not be putting the injection system
back on from all that has been said and what I have read about.... I dont want to rebuild this motor and have the chance of the oil system failing again.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
Re: Oil Injection or NOT

Ron, You never told us the OMS Oil Injection system had failed. The oil injection system on your motor is a very good oil injection system, argueable the best ever made. How do you know it failed?

BTW- An oil injection system failure would damage all the cylinders at once. If you had trouble with only one cylinder, it is very likely the Oil injection system is innocent.
 

Teammuir1

Seaman Apprentice
Joined
Aug 13, 2010
Messages
45
Re: Oil Injection or NOT

I went back on all the posts I have done here.. and YOUR right
I am sorry for that.. see I have another post about this motor
as well... I guess I got the two confused.. lol...
The original owner stated that the oil system failed on him.....
he took off the system and started to add oil to the gasoline.....
I did not talk to much to the original owner.. for reasons that I
will not go into here... ( might affend someone. ) lmao.....

SO I was told that the system failed HE TOOK IT OFF.......
My apologies.. for not mentioning it sooner.. I did mention
it on the other post I have.........
Ron
 
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