1985 johnson Gt 150

[85Skeeterman]

I own a 1985 Johnson GT 150 hp. outboard with updated head gaskets to lower compression as a fix for unleaded fuel. It originally used gapless spark plugs UL77V.
My question is can I now use the Champion QL77JC4 plugs in this engine with my compression around 90 psi instead of original 125 psi.

Thanks
85Skeeterman

 

[boobie]

You can use either plug. They both have the same heat range.

 

[Faztbullet]

Did you install the kit? Head gaskets are the same between stock and low compression kits, it the heads that's different. They did make a low octane gasket but it should have only dropped compression about 10psi. Unless your in a foreign country or a area where gas is just crap run the stock head or gasket. Two strokes don't care if they drink leaded or unleaded fuel..

 

[85Skeeterman]

In response to Faztbullet question I did in fact change those head gaskets my self in about 1987. These head gaskets were OMC'S fix for running non leaded gas according to the dealership in my area.

I did notice when I changed them that they were thicker then the original. I also thought that it was quite a drop in cylinder pressure.

Around 1990 I changed 3 scored piston which was a issues I had with oil injection system. I now mix my oil with my gas and haven't had any cylinder issues since then. I do reiterate that that the change to new type head gaskets did significantly lower my cylinder pressure to around 90 psi.

In many post I have read where viewers posted concerns about cylinder pressure being around 80 to 90 psi..

All I can say is my cylinder averages around 90 psi and my old 1985 Johnson GT still runs good,

Thanks to all responses

85Sketterman

 

[85Skeeterman]

In response to Boobies answer concerning gap or gapless plugs for my 150 hp Johnson.

Thank you!!

85Skeeterman

 

[racerone]

Correct the early kits were thicker head gaskets.------People responding can only go by / use the information posted.----Not there to inspect motors first hand.-----When certain motors only show 90 PSI there are problems.