what caused a hole in my piston?

[Rydog]

i was riding in the sand dunes at full throttle in 5th gear when i heard a bang and my motor quit. about 5 minutes before this i thought i heard a metal rattling sound but ignored it because i thought it was a flag bracket that was on the bike. i pulled the plug and it was melted and powdery white. when i took the tank off i was surprised to see that the top of the carb was off. the throttle was working fine for the 15 minutes i was able to ride it. i pulled the cylinder and the piston had a hole in the top of it. the cylinder looks ok. the bottom end looks like it has shavings in it. i was running a br7es at the time.(it calls for a br8eg) do you think it damaged the bottom end? i want to tear it apart to save $ but heard it is pretty difficult. did this occur because the carb allowed too much air in causing it to run lean did the sand entering the carb have anything to do with it? how does an es plug perform compared to an eg plug? what should i have done besides clean the carb out and have the bottom end checked out? thanks for any help.

 

[A-RustyDemon]

Yep.. per ignition lean burn thru.. cause by lean fuel air condition combined with a to hot of plug. Your gonna have trash in the case. so get a manual your going to be breaking the case. As for the eg V's es it's just different electrode design.. heat range is the biggest key in a plug choice.. The heavier load placed upon the motor from the bike running in the sand requires a richer jetting and sometime a cooler plug to help keep the cylinder for melting down. Expensive lesson to learn but if you don't clean the trash out of the lower end it could get worst. So get a manual and good luck.

 

[MikeyG]

MOD EDIT
Next time I have to edit one of your posts like this you are OUT OF HERE