How do I "Break the edges" on a cylinder bore?

[Mik]

I'm working on this v6 Evinrude block, and had one cylinder bored out (.030) and the other's honed. I'm working on trying to break the edges, to keep the rings from catching. I can use my dremel tool to get at the upper lip, but I'm finding it hard to get at the lower lip of the port. How is this done? is there a special type of file that is used?<br /><br />Mik

 

[Dhadley]

Re: How do I "Break the edges" on a cylinder bore?

The deburing should have been done at the machine shop as part of the bore & hone process. If it was done by an automotive shop or someone not familiar with boring an outboard block you may want to have it checked over by a marine machine shop.<br /><br />However, if they honed it with a ball hone or brush hone thats all thats needed. If it was rigid honed we use a dremmel tool and a rubber bit impregnated with stone. <br /><br />It doesnt take much, just trace the edges of the ports at a slight angle.<br /><br />Again, if it wasnt done at a marine machine shop I'd have someone measure the finished bore size.

 

[Mik]

Re: How do I "Break the edges" on a cylinder bore?

The three places that I interviewed to bore the block all said that they leave it up to the customer to break the edges.<br /><br />Thanks, I got it done.<br /><br />Mike

 

[Dhadley]

Re: How do I "Break the edges" on a cylinder bore?

Not a good sign. You need to find out what they used for a finished bore size. You dont want to stick the new piston.