Disintegrated piston

[livefastridefast]

Ive installed a 50mm bbk, ran great for about a month then it seized up on me. I took it apart and found it to be alot worse then expected, the piston was damn near disintegrated!! Ive also installed a 24mm carb and been using the factory jets, main jet seems to work great but pilot jet needs a lil adjustment, been waiting on the new pilot jets. Ive been trying to diagnose this issue before i throw the new one on. Any suggestions on what could have caused this would be great!!

[acvw74]

Do you have any pics?
Sounds like it might have been running lean an overheated.

[2stroked]

You mentioned a new carb, what kind of air filter were you using?

Sounds like it was running way, way too lean and just ate itself. With more air going in, you need to add more fuel, a free flow filter/pod filter/sock whatever is going to flow way more air than stock so stock jets aren't going to work.

[GrumpyUnk]

When you installed the BBK, did you re-install the shroud around the cylinder and head? If not, you found out the expensive way that the shroud is necessary for longevity.
Did you check ring end-gap before installation? If the rings were a smidge too large, the gap when installed square in the cylinder bore might have been to small. When the rings got hot during operation, if they expanded enough to have the ring ends touch, then further expansion of the ring would be problematic. Excessive ring tension on the cylinder wall surface could result, and wipe all oil off the cylinder wall instead of leaving a bit for lubricant. Alternatively, the rings could have galled the cylinder wall, and caused the piston to get too hot, and in turn start to interact with the cylinder wall with the end result being scoring, lack of compression, and, circumstance depending, destruction of the piston.
Or you could have had a defective piston, or a piston that reacted to pre-ignition due to increased compression ratio and inadequate octane fuel.
Your choice.
tom