CA95 Piston

[Rgervais]

Hi everyone
Quick question - does that right piston look correct? There is a 'hole' in the top, doesn't go all the way through, but its perfectly round like its supposed to be there?
Thanks in advance
Roger

 

[ancientdad]

Roger, the picture is barely larger than a thumbnail so it won't zoom, but I seem to recall some pistons had a "dimple" in the dome.

 

[Rgervais]

Is this pic better? And thanks for the quick reply

 

[mike in idaho]

I would find another piston, that one's been kinda warm at one time or another. What do the sides look like?

 

[ancientdad]

Is this pic better? And thanks for the quick reply

That picture zoomed in nicely. Seeing what the rest of the piston looks like, including underneath the dome, would be helpful but as Mike said, it looks it may have gotten hot. The other piston is a 3rd oversize, looks like 0.75 stamped on the dome

 

[Rgervais]

The sides are scored, but I don't feel anything with a fingernail. Pic below.

 

[ancientdad]

That shows it was exposed to excess heat, either by reduced lubrication or possibly by a bore job not given enough clearance

 

[mike in idaho]

Overheating and/or detonation, material is eroded around the size markings, looks like it was about to burn all the way through that hole. When it goes back together be sure to get the carb and ignition settings sorted out so it doesn't happen again.

 

[boddy]

The sides are scored, but I don't feel anything with a fingernail. Pic below.
View attachment 7603

You might also want to check that the valves are not bent. Looks like a witness mark on the exhaust side of that piston.