Top end question

[Jferdi03]

I cracked a piston in this new bt100. There's nothing loose and the pins are still intact. Should I sand down by the spark plug? What could of caused this?

 

[Wrench]

Wrong piston pin height piston There are two different piston pin height pistons, You must have the wrong piston

Unless your S/P was too long and the piston hit it

 

[Frogslayer]

How did it happen? Was it detonation from too hot of a spark plug and too low octane gas?

 

[Wrench]

How did it happen? Was it detonation from too hot of a spark plug and too low octane gas?

I noticed the head looks brand new like he only started it once and the piston broke.
IDK Maybe he cleaned off the carbon before he took the pic

 

[Frogslayer]

I noticed the head looks brand new like he only started it once and it broke. IDK Maybe he cleaned off the carbon before he took the pic

Ah I see now, almost could be bad casting

 

[Jferdi03]

It was the stock piston, made one ride around the block

 

[Jferdi03]

I'm buying a zeda80 and getting a free piston for the bt100 with it. Should I sand that stuff down before I install my new piston? Don't want to break it again.

 

[Jferdi03]

Had a better look and it looks like the pin that holds the piston in place was the cause..

 

[Wrench]

Had a better look and it looks like the pin that holds the piston in place was the cause..View attachment 106691

Yep that'll do it, another quality part made out of Chinaesium

 

[Wrench]

I'm buying a zeda80 and getting a free piston for the bt100 with it. Should I sand that stuff down before I install my new piston? Don't want to break it again.

Check the squish before ya start the next one. Just double check and make sure the piston don't hit the head.