Fixing my Johnson

[smoothmove]

There now that I got your attention.

A friend of mine has a mint condition 1978 115 hp Johnson outboard that appears to have clipped a ring in the exhaust port and buggered up the piston. Actually, the bore looks really good and I'd like to try and fix it for him without buying a new powerhead assembly. Has anyone ever done this? He's got nothing to lose besides a few parts if the repair doesn't work. Is there any shop manual other than Clymer that might be more helpful?

Any other suggestions?

Eric

 

[SKYCHENEY]

I get emails about this quite often.

 

[krush]

Many 2 strokes have a pin in the ring grove to prevent the ring from rotating and getting ripped off in the ports.

It's not too hard to rip these puppies apart. Best way to do it is remove just enough stuff so you can lift the powerhead off and then remove the rest of the stuff on the bench. Not sure about that engine, but some mercs had no removable head....u stick the pistons in from the bottom.

 

[34Hatt]

That actually happens more then you think. They never put a bevel on the ports! Which is something you want to do. It developes a fairly sharp edge piston rocks a little and the ring gets caught. So see how the port edge is?

You need to pull the power head split it, clean check bore size and for roundness, bevel the ports hone & clean again. Should have heads milled to be flat. Get a OMC manual and it takes you through it step by step except for the beveling of the ports. Learned that from a Outboard mechanic with 50 years of experience. They are fairly simple and only use the correct gel seal on the two halves of the block when going back together.

 

[DLCameron2]

Try VIAGRA it works for some people.

DC