Piston Rings - Chamfered edges or not?

[glennschumann]

I just bought a new golf piston for my 025 from a seller on ebay, but the rings had a bit of surface rust on them, so the seller sent me new ones. (Good seller to deal with) I noticed the new ones are a bit different, however, and I don't know if it makes a difference...

The first rings he sent have a perfectly square edge (Where the friction surface meets the top or bottom of the ring) and the new ones have a slight chamfer so that the sealing surface is slightly less. They are the same in all other ways.

Does this make a difference? If I recall, all of the other rings I've used have the square edges. Maybe this design lets more lubrication between the ring and cylinder wall, or breaks in faster, or seals better (smaller surface area, same pressure) or...? I don't know what brand the new rings are.

Like to know what you all think.

 

[Jacob J.]

Light surface rust isn't going to be an issue. I would have installed that piston and rings as-is. That light surface rust is going to last all of 1.93 seconds after you start the saw up.

 

[glennschumann]

Thanks for the thoughts... I've buffed rust off of piston rings before, but this was actually pretty deep, and I'd fear loosing compression if I was able to get all the rust off. Since this is a clamshell design engine, I'd rather get it right the first time rather than taking it all apart again...

Just wondering if there is a bit of wisdom (opinions) out there about chamfered vs. non chamfered rings in saws.

 

[Jacob J.]

You'll get about the same wear out of either set. Some manufacturers chamfer the rings to protect against snagging a ring in a port that's not properly dressed. It ends up being six one way, half a dozen the other.

 

[will g]

I would like to hear more about this. I ran into this with my 026, emailed the seller and he was not sure; however I went ahead and used them and the saw is running great, cranks easy and has good power in oak. Only thing I can tell is it pulls (cranks) a little easier than my other 026. I don't have a gauge but the power seems about the same on both saws. It makes sense that they might break in and seal quicker. This is the first saw I have repaired but I am happy so far. Will

 

[50blues]

automotive rings almost always have a chamfered edge. something about as the rings slide they are suppose to seal better.

Don't know to much about this.