gas or gas with oil mix?

[jcgizmo69]

I have and '84 Mariner 75 hp motor. I am being told that this motor used a 50:1 oil mix ratio. I thought this motor was straight gas! Can someone help? How do I know if it is straight gas or a mix?

 

[NelsonQ]

Re: gas or gas with oil mix?

That`s a 2 stroke engine requiring gas and oil mix. I don`t know the ratio but I believe you`re correct in stating 50:1 on that engine (friend has the 87 60HP version and its 50:1 gas and oil mix)

Running straight gas will provide no lubrication. Do you have an inline oil pump on that engine (oil reservoir and pump sitting between the fuel tank and the primer bulb) that mixes for you

If not, you`ll need to mix it in the tank

Lastly, welcome to iboats forums.

 

[jcgizmo69]

Re: gas or gas with oil mix?

Thanks for the welcome! I am new to boating so I don't know what is meant by 2 stroke. I saw 4 spark plugs so I thought it was like a 4 cylinder? Anyways, there is nothing in between the bulb and tank so the mixing will be done by me.

 

[achris]

Re: gas or gas with oil mix?

All 2 stroke engines need oil in the fuel. Older engine got it by the user mixing the oil into the petrol. Newer engines have 'oil injection' where the oil is mixed with the petrol (usually) before the fuel reaches the carb(s).

Unless your engine has an external 'auto-blend' system, you need to add oil to the petrol, at a ratio of 1 part oil to 50 parts petrol.

Chris...............

 

[NelsonQ]

Re: gas or gas with oil mix?

Thanks for the welcome! I am new to boating so I don't know what is meant by 2 stroke. I saw 4 spark plugs so I thought it was like a 4 cylinder? Anyways, there is nothing in between the bulb and tank so the mixing will be done by me.

you're correct. Four plugs means its a four cylinder engine. And, your engine is a 2 stroke.

If interested, I've added some verbage below I pulled from the web quickly to explain.

Here is the differences between 2 and 4 stroke engines if you want even great details, google 2 stroke engines and you'll find a ton of resources.

Four Stroke

As the name implies, four different strokes:

1. intake stroke
2. compression stroke
3. power stroke
4. exhaust stroke

On the intake stroke of the piston, the piston descends from the top of the cylinder, reducing the pressure inside the cylinder. A mixture of fuel and air is forced (by atmospheric or greater pressure) into the cylinder through the intake (inlet) port.

The intake (inlet) valve (or valves) then close(s), and the compression stroke compresses the fuel?air mixture.

The air?fuel mixture is then ignited near the end of the compression stroke, usually by a spark plug. The resulting pressure of burning gases pushes the piston through the power stroke.

In the exhaust stroke, the piston pushes the products of combustion from the cylinder through an exhaust valve or valves.


Two-stroke

1. Power/exhaust: This stroke occurs immediately after the ignition of the charge. The piston is forced down. After a certain point, the top of the piston passes the exhaust port, and most of the pressurized exhaust gases escape. As the piston continues down, it compresses the air/fuel/oil mixture in the crankcase. Once the top of the piston passes the transfer port, the compressed charge enters the cylinder from the crankcase and any remaining exhaust is forced out.

2. Intake/Compression: The air/fuel/oil mixture has entered the cylinder, and the piston begins to move up. This compresses the charge in the cylinder and draws a vacuum in the crankcase, pulling in more air, fuel, and oil from the carburetor. The compressed charge is ignited by the spark plug, and the cycle begins again.

Hope this helps.

 

[jcgizmo69]

Re: gas or gas with oil mix?

Yes, it helps a little! Thanks!