FZRSupport: the FZROnline Archive

So I built an FZR660 motor that's in a 400 frame a few years back and haven't gotten to ride it much. After sorting some basic issues at the time, I realized there was an oil leak from god knows where. I was thinking that it was related to the job I did to seal the two halves of the case, but I also had a slight crack in the front of the lower half of the case that was previously JB welded. I had chipped off all of this and resealed it but I guess didn't do the greatest job (most def leaking there as well).

The bike sat for about 2 years collecting dust until I am now finally tearing it down again. So I pulled the motor the other day and have the jugs off. Taking the wrist pins out was really difficult. When they were initially installed, they slid right in. Taking them out, I had to use a socket and small hammer to tap them out. It looks as though the wrist pin hole on the pistons has stretched! I only put a couple hundred miles on the bike after the rebuild. I do know that my brother took it out one time, unbeknownst to me, for a joy ride and I'm guessing her revved the hell out of it, plus I believe the bike still has the 400 ignition module, which has a higher rev limiter (not good for the 600 motor) which he probably tach'd out at.

So I guess my question is, would the wrist pin wholes stretch out like that prior to frying valves etc? Has anyone ever experienced this before? I did have some overheating issues that I was working out as well, so maybe this played a role? The wrist pins and wrist pin holes on the connecting rods seem fine.

Link to the pictures below: (still new at posting pics, so click on the 1st link below if they dont individually show up in post)
https://imgur.com/a/c70beES






This is the parts list of the motor for reference:
-FZR600 lower end (cases, crank, transmission)
-YZF600 Cylinders (2001)
-YZF600 pistons (2006)
-YZF600 head, (2006)
-YZF600 carbs (1999)
-FZ600 (fazer) connecting rods (5DM)

So, maybe I jumped the gun a bit with the piston stretching thought. After further inspection, and looking at some photos of other pistons online, it seems as though the difficulty of removing the piston pin was due to a burr being created on the wrist pin clip grooves, not the hole stretching out. Which again, brings up the question as to why the burr occurred. I did not have this burr when removing the stock FZR pistons. Next step i guess is to check big end to crank clearance and tilt.