Except I would Not suspect a piston pin retainer to be square in profile... More like the Cage from the Cheap *** Cam bearings.... Maybe
should be able to see that easily at this time.

 

ill check again when I get back to the house

 

That my friend is the inner cam bearing cage after it explodes, motors coming apart period.

 

soon further investigating it was a wrist pin retainer clip I have replaced them all now with 3 circle clips from kB preformance I have also completely cleaned and reassembled the bike the breather gear that was stuck was not damaged I have cleaned the breather gear section of case has small indent where the metal was but used emery cloth to take the taper away and good cleaning there should be able to fire up tomarro and break the motor in again lol

 

Square sectioned??... and Now, a different Clip???
Only the Recommended [supplied] keeper should be used on any given piston... it is a system... unless ya do Buttons.
Spiro locks are square sectioned..and the piston "groove" matches.. the CirClips are round sectioned...and the groove is also...

 

It’s a round 3 wrap spiral clip on pistons use

 

This isn't going to end well...

 

Working on new motor lol n I’ll run that one til it’s conpletly done lol

 

There may be a reason the clip liberated...

Have you checked connecting rods for straightness?

 

Yup, the older double timken lower ends throwing a wrist pin keeper means one of 3 things, bad assembly on a fresh build , rods or crankpin are roached or the cranks scissored.