Reusing Old Piston Rings

K

klr

New Member
I'm working on a '77 KZ400 with 10k miles. It's a rusty rat and I got it with the top end removed. The cylinders look great. I removed the top ring from each piston, pushed them into their respective cylinders, and measured the ring end gap. The end gap is on the tight end of the spec given in the manual.

The obvious solution is to buy new rings and hone the cylinders, but rings are rare and when they do pop up on ebay they are in the $50-$60 range per cylinder and it's not in the budget to spend that much on this project at this point.

So, can I get by with honing the cylinders and reusing my rings? Should I just reassemble without honing?

Any opinions based on experience would be appreciated.
 
Why hone the cylinders? If you have confidence in the engine slap it back together and run it. Not sure re-honing is a good idea with used rings.
 
I would hone just a tiny bit. That will establish a cross hatch that will re-seat the rings. There is little likelihood that the rings will go back in with the gaps in exactly the same place as before, so they may still have to seat a little. Cross-hatching will help assure that they will seat in a reasonable time.
 
AlphaDogChoppers said:
I would hone just a tiny bit. That will establish a cross hatch that will re-seat the rings. There is little likelihood that the rings will go back in with the gaps in exactly the same place as before, so they may still have to seat a little. Cross-hatching will help assure that they will seat in a reasonable time.
Click to expand...

That's the way I was leaning. I can put the rings back on the pistons they came from, but no way can I tell where the ring gap was.
 
The rings are going to spin on the piston when it's running (slowly) they don't stay stationary.
But a light hone won't hurt if the rings are still good.
 
SONICJK said:
The rings are going to spin on the piston when it's running (slowly) they don't stay stationary.
But a light hone won't hurt if the rings are still good.
Click to expand...

The rings can "walk" to a different position over a long period of time. I wouldn't say they "spin on the piston." Their positions move very little, in reality.
 
I was just saying I don't think they wear spots in the walls where the gaps are unless the rings are stuck
 
Very true. It's just that a bore is not necessarily perfectly round or free of flaws, and rings will conform to the imperfections in the cylinder wall, still effectively sealing even with light scoring being present.
 
I don't see the down side of honing... I'm of the opinion that the pattern is there, not only for promoting quick ring seating but the cross hatch also holds the oil on the cylinder for better lubrication.
 
IIRC, rings rotate at around 7rpm. Just don't ask me where I ready that particular factoid because I have no idea where it came from.

A very light home should help to just clean off any high spots. Wash the bores out after and wipe with a clean white rag. Repeat until the rag comes out clean.
 
I've built a a lot of motors with used pistons and ring if they still have spring to them and are in spec keep the piston with it hole bust a ball hone thought it and put it together with 2stroke oil as assembly lube.

rule of thumb if teazer and adc are kool with it take it as gospel, so the real question is are you ready to testify
 
...and if all three of us agree it's a conspiracy

TheBrush.jpg


~kop
 
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