1984 johnson 155 question

[BEKO1212]

someone told me that this motor is made to use low octane fuel like octane in the 70,s.he also said to lower the octane level by adding diesel with the fuel.does that sound right or does this guy not know what he is talking about.

 

[emdsapmgr]

Re: 1984 johnson 155 question

The commercial engines are designed for use on heavy work boats in all parts of the world. I some areas, the user may not have access to the same fuel as available here in the U.S. For instance, most outboard engines are made to run on 87 octane fuel. The 155 is designed to run reliably on 75 octane fuel. Your engine will run fine on any 87 octane fuel here in the U.S. They have many non-standard parts by factory design. The normal gear ratio in a V6 is 14:26, the ratio in a 155 is 12:27, a much lower ratio.

 

[BEKO1212]

Re: 1984 johnson 155 question

does the gear ratio mean a johnson 150 is faster than a 155?

 

[emdsapmgr]

Re: 1984 johnson 155 question

The gear ratio means that the engine has more torque and less speed with the same prop. You can try to change props to compensate for the ratio difference, but will probably find you won't be able to match speeds with a 150.

 

[BEKO1212]

Re: 1984 johnson 155 question

and while qe are tlaking about this motor what should the compression readings be? i got 79-81 on all 6 cylinders.does that sound about right?

 

[emdsapmgr]

Re: 1984 johnson 155 question

That's low for a normal 150. Because yours is a commercial engine and is made to run on low octane gas-it could be normal compression. Another reason it won't with a normal 150.

 

[BEKO1212]

Re: 1984 johnson 155 question

ok another question.. is this motor a 2 stroke or 4 stroke engine?

 

[emdsapmgr]

Re: 1984 johnson 155 question

2 stroke.