Johnson 20 troubles

[fowlmood77]

Having problems getting all the power out of my motor. She revs fine and has power out of the water, but when under load I am getting no where near the top end I use to get. I thought it might be the dreaded ethenol problems so i took apart the carb the other night. Everything looked good, so I did a compression testand found 120 on both cylinders. I am stumped to what might be causing the power loss. I did find one plug that had a little wet fouling on it. COuld this cause a drastic loss in power? It is almost like I added 500lbs to the boat, but nothing like that has changed.

 

[lckstckn2smknbrls]

Sounds like it's only running on one cylinder.

 

[Quackrstackr]

Sounds like it's only running on one cylinder.

Agreed.

 

[russ010]

dude I had the same exact problem with my Johnson 20... ended up being either bad gas or a bad ratio mix. I emptied the gas tank and put new gas/mix in and that sucker is back to where it used to be again

 

[Zum]

Am I reading it correctly that it's running well or atleast sounds like it is?
Compressions good.

I'm thinking spun hub....

 

[Quackrstackr]

The wet plug leads me to believe that he has a non firing cylinder.

They will run like a banshee without a load on them even though they have dropped a cylinder.