Has anyone ever experienced this before
3/4 of a spiralock was found in oil pan.
What are possible causes. I caught it in time just want it not to happen again. Ty

from (piston) pin or (hyd) lifter. EDIT I missed the spira lock so that elims the lifters

Possible causes?

It was in the pan from the previous freshening, or it broke this time around and ended up in the pan.

Sometimes they break....... stuff happens.

The motor is talking to you saying it is broken, time to find out where and why
OP, you need to take the pistons out to find which one is broken and then figure out why it fail to make sure it doesn't fail any more of them
I've had pistons that didn't have enough end play on the spiral locks so they would seat completely in the machine grooves
Most piston makers want from .0010 to .0030 end play at room temps with no oil My thinking on this is that a lot more(.003+) clearance is better than a tiny bit to little, less than .0009

It’s possible........ but not all that likely that piece made it into the pan without “touching” a few other parts along the way.

Might be a few nicks or scratches that could use some attention.

Pull the pistons. See whats broken. Hope the cylinder wall survived. If that stuff all looks good, re-evaluate your washing procedure for a block that's being made ready for assembly.

The open end of the pin (if that's what happened) will slide over and dig a trench in your cylinder wall faster than you think.
Got to come apart, the block is too $$$ to lose.

My initial thought too. It does seem like a lot of pistons today are machined for double locks. Maybe for this reason?

Many race pistons that use spiro-lox, use two on each side.

Not that it really matters at this point........ it should come apart anyway, especially if you don’t know if your pistons used singles or doubles per side.

This is a reminder to closely inspect the lock type you get, and especially the depth, shape and finish of the groove. Not recently, but I've see grooves not deep enough (lock cannot expand fully), or not wide enough for both locks (one is on the edge), and "new" locks that were obviously different diameters in their relaxed state, or apparently had been installed and removed (spiraled, so that the ends were overlapping, but not quite touching).

Good shops will never do that? If they haven't had a bad one in 10 years, are they really going to examine 48 small areas (8 × 4 + 16) without billing you?

Old Harley mechanic's rule: if the lock ("L" shaped cross-section in those days) is at all distorted, or does not "SNAP" completely on to the pin groove, throw it away.

Any of these could be a $$ in the making.

Keep us posted on your findings!

Good info (I learned something today).

You must have a heated garage to just find that now
Who do you use>

I know someone that this happened to recently, it was a stroker motor. I don't remember who's kit, but it only used 1 spirolok per side. Pin killed the bore.

I've seen this more than once on Harleys in my shop.Worst case,you'll end up with two grooves in the radius of the bore. If you are lucky and the other part of the retainer is still in the pin bore,then I'd say good timing!

Icon pistons now come with a single piece three layer spirolock, is that what you saw?

Cab,I have Icons with those spirolocs getting ready to assemble. should I use 2 per side or something else.?

What I remember is only enough keepers to do one per side on each piston The pistons are machined so only their keepers will fit in those pistons
No spares Be careful on installing them

i just installed ICONs a a stroker 496,they came with one triple wound SL per side,they went in nice,i cant see them coming out unless there was a gltch puttin them in.