Johnson 50HP Running Terrible

[loozo730]

I have a Johnson 50 HP motor on my Ski-King boat. I don't know much about outboards, as I come from the 4 wheeled world. When I first bought the boat, it ran fine and would do around 25 MPH. Then a while ago, I was out zooming around and the motor made a loud clunk noise. I stopped and let it cool off for a minute and tried turning it over. The starter would engage the flywheel, but the flywheel seemed very difficult to turn. I then tried to turn the flywheel by hand, and it was very difficult. I was towed in and I bought a hose adapter to try in my driveway. I then took it out yesterday, and it seemed very sluggish, maxing out at about 10MPH. Then it clunked, and the flywheel was difficult to turn again. I am pretty sure there is neutral safety switch, so its not in gear. The propeller spins freely in neutral. I also bought new spark plugs and battery recently.

Also, is there a way to hook my stock tachometer to the motor?
Thanks!

 

[R.Johnson]

Re: Johnson 50HP Running Terrible

What model, or year is the motor? A loud clunk, and a hard turning flywheel spells trouble. Sounds like something is trying hard to come apart.

 

[rolmops]

Re: Johnson 50HP Running Terrible

Sounds like you only have one piston left while the other is probably garbage.
Do not try to run it until you have discovered what clunks.

 

[tx1961whaler]

Re: Johnson 50HP Running Terrible

These are R.J. 's FAVORITE motor! . I think he said yesterday that if Jesus had an outboard, it would be one of these 50's... (no sacrilege intended...)

Was this motor's temperature running hot? It could be running hot, and trying very hard to seize up on you.
<OR>
It sounds like a loose connecting rod is is really trying to find some fresh air through the side of the block