Melted piston

[Morgan Kane]

The Vito piston on my sons Blaster has melted hole in it. Bored 10 hours ago and jetting on the richer side. Any diagnosis?

 

[speedyslyder]

seems like it tends to happen easier with the pie cutted exhaust piston's.
have seen several of them on here just like yours.
what is your setup/mods
pipe
main jet ect.
the ports on cylinder have to be chamfer properly as well.
did you ever do a leak test after rebuild?
was it broke it properly with heat cycles?
http://www.blasterforum.com/threads/about-air-leaks-save-your-engine.55537/#post-763164

 

[Awk08]

I'm with speedy /\
heat cycles then retorqued head and base to spec ?
leakdown tested ?
green paper base gasket ?

 

[Larry's Shee]

You might see it more with the pie cut is people don't know that it's almost like being ported and jetting isn't compensated.
They are a forged piston made by Wiseco . The rings are dropped an equal amount so they are are correct distance at pie cut.

Simple case of lean melt down .