To bore or not to bore

[Archnawan]

I have a 78 115 evinrude that sheared rings on the starboard side causing some scratching in the clylinder walls. It is not deep and I beleive I can smooth out the scratches with 300-400 grit paper. I have heard some horror stories about getting outboard's bored over, so would this be a better option than getting the starboard side bored assuming I still get good compression after sanding the scratches?

 

[R.Johnson]

Re: To bore or not to bore

The best way would be to measure the cylinder bore. If you don't have the means to do this, any machine shop can do it for you.

 

[Dhadley]

Re: To bore or not to bore

Once the machine shop has measured it you will know. I'd bet youre going to bore all 4. The rings broke from coking almost assuradely. That means the motor was being lugged. Lugging creates heat and heat promotes coking. The rings stick in on the back side and eventually the gap end shears off as the piston loses support.<br /><br />With all this heat the cylinders are going to be out of round not to mention over 25 years of wear. Boring is the only way to straighten it out properly. Boring is no big deal.<br /><br />I'd almost bet every horror story you heard about boring was due to an automotive shop boring an outboard. Not unusual at all.

 

[Chinewalker]

Re: To bore or not to bore

At the very, VERY least, skip the sandpaper and borrow a good Sunnen straight hone to clean up the existing bores. Even if you do that, check them again for tolerances when you're done....<br /><br />- Scott

 

[Archnawan]

Re: To bore or not to bore

Your probably right about an auto shop doing outboards so how will I know if they are qualified? Can anyone recommend somebody? I live in Richmond, Va but I guess I could ship them also.

 

[Dhadley]

Re: To bore or not to bore

I would suggest someone like Mar Fab in Tennessee who can do the machine work and supply you with everything you need to reassemble. Or they can reassemble. Some of the best and smartest folks in the business. <br /><br />There are many fine marine machine shops around like Flagship, Tribble, Blackburn, Roehrs, Riverside etc. I will be happy to get you numbers if you like.

 

[Archnawan]

Re: To bore or not to bore

MarFab looks like a nice place to do business with anywhere like that within driving distance from Richmond, VA would be great!<br /><br />Otherwise I'll see about shipping to MarFab.<br /><br />Thanks!

 

[Dhadley]

Re: To bore or not to bore

Mar Fab -- talk to Kurt or Dan at 931-738-2815.