'78 Evinrude 6 HP Piston Wear

I picked up a poorly running '78 6 hp. Compression is 50-55. Cylinders are 1.9385, Pistons are 1.934. Do you think I can clean these up and reuse them? I'll just be using it as a kicker.

You measure at skirt or lands?

With rings freed up it will run nicely again.

>>You measure at skirt or lands?

Skirt at 90 degrees to piston pin.

>>With rings freed up it will run nicely again.

Thanks!

Don’t forget to make sure the head is not warped. I had an 8hp that only showed 60ish psi. Once I decked the head, (it was warped .005”) level, compression went up to 112psi.
http://www.marineengine.com/boat-fo...ow-much-does-a-warped-head-affect-compression

What do the cylinders look like? Can you post a photo? Nice shot of Pistons. Wonder what happened....overheat? What's the water pump look like? If running lean caused the problem, you should check the main jet size....hiding in base of float bowl. Carefully take it out. You may have to clean it while it's in place, I often see where some one has tried to get out the jet and messed up the threads as well as the slot for the screwdriver. You might want to take an old but decent quality screwdriver and grind it the perfect size to fit into the port and wide enough to grab the jet securely. Lastly look at the color of the paint on the cylinder head and if it is discolored then we can assure ourselves that it was badly overheated. That might mean that the piston rings have lost their tension and you may have to replace some parts then.
I'm about to ship out a 1978 6 horsepower Evinrude that I am rebuilding for a sailboat out in Virginia Beach. Since it's 0° here it is a little difficult for me to test it in the water barrel. Although the spark jumped a strong 3/8 in with the tester I decided to remove the coils because I noticed some cracks. So this motor, once running, would have developed a miss on the cylinder with the hole in the coil occasionally shorting out to the stator plate. So what's this tell us? It tells us that a spark test is not proof that we are ready to go sailing, eh? By detailing this motor in such a thorough manner, I can rest assured it should run pretty well when it arrives out in Virginia.
So when we see a problem that is indicated in your piston photos, we must correct the condition that caused it.

A 1978 model 6 HP Evinrude does not have coils under the flywheel !!

Sorry, it's a 1976, thanks, Racer. Guess it's my "aldhiemers" kickin' in. Since I hit 65, I place less importance in numbers than I should.

I don't think it overheated, it's just been neglected and abused. It's a saltwater motor, has broken bolts, bad coils, bad powerpack, tip of the idle mixture screw is broken off in the carb, stuff like that. I probably should have passed it up, but I wanted to see how an old style 6 hp would run with a CD ignition. The water pump is the upgraded version however. Cylinder walls are smooth in spite of some light discoloration.

Those motors run really , really well.------Universal magneto or that super reliable electronic magneto, makes no difference.

Yes, almost every reasonable effort to restore these little twins, is well worth it. There should be a little lite honing done in these cylinders....I have a little drum and fit it loosely with some 180 to 240 wet or dry paper. Hone to develop a lite crosshatch while using some soapy water. I would order a new set of rings and after carefully cleaning up the pistons, then reassemble. You need to be careful with the aluminum surfaces so not to scratch them. Clean out your threaded holes there with a close tap, (snub nose). Buff all bolts with wire wheel, then replace your lost zinc coating with a little nickle anti - seize. Surface both block and head with 180 to 240 wet or dry, using a nice flat surface and soapy water. Alternately rotating clockwise, then counterclockwise and/or figure 8 motion. If you do this correctly, and gasoline is still available, this little twin will still be running sweetly in 2050 and beyond.