Lacking Power at Full Throttle - 1984 Johnson 60HP J60ELCRE

[screwdriver724]

Hey there, just looking for some tips with this motor. Starts easily most days, idles without issue, and will putz around the lake. When I get to a place where I can open it up, I am getting to ~12MPH on a 14 foot fiberglass bass boat that never gets on plane. So the motor works fine in all of my local no-wake scenarios, but at increased throttle, it just doesn't have the power.

This is new fuel and new sparks plugs right off the bat. I tested the ignition coils with a multimeter and both came back good. Compression testing (cold) came back at 151 on the top cylinder and just over 120 on the bottom. Fuel filter is good and clean and pump appears to be good as well.

My next thoughts would be to check either the carbs or the power pack based off my limited experience. Would anyone else look elsewhere? Any other recommendations?

Thanks!

 

[racerone]

The low compression is an issue.----Pull the cylinder head off now.----Lucky you if it is a blown head gasket.----But I think you might have a scored cylinder wall / damaged piston.----Motor would need to come apart for major $$$$$ repairs.

 

[screwdriver724]

Ok, thanks for the info. I will say one of the last times on the muffs in the driveway, I had a good amount of white smoke... That would point towards the headgasket in theory right?

 

[racerone]

Just take the head off and have a look !

 

[screwdriver724]

Just take the head off and have a look !

Yup, a beer and a few tunes tomorrow in the garage might just be warranted.

Also wanted to update this. Apparently my "helper" can't read a gauge. The compression test results were actually 150\135 between the two cylinders... Makes me feel at little bit better at least...

 

[rowerowe101]

adjust the high speed idle mixture on the carb, then clean the carbs well.. I would try that before breaking into the head... also checking pressure on fuel pump

 

[racerone]

rower----There are no mixture adjusting screws on the 2 carburetors.

 

[screwdriver724]

Good Lord. That's all I'm going to say. Started taking the motor apart today. So when I replaced the plugs, I put in the same as what was in the boat. That's my own stupid fault...

The previous owner had Quicksilver gapless plugs.... in this 1984 Johnson. The plug model came back to be for a Merc too. Could that be part of my issue? Anyways, I got pretty mad today when I saw what plugs it should have. New plugs in and did a cycle of SeaFoam through it as well. Tons of smoke, the usual, and the cleaning went well.

Here's one more funny thought though. I retested that bottom cylinder after the SeaFoam cycle and it compression tested at 148psi. Going to try it cold later and see how it relates to the original 135psi cold test.

Anyways, hoping this was a waste of time for you all and it runs great tomorrow when I take it out with the right plugs in it.

Thanks everyone for responding and offering suggestions!