dropped valve

[400exBRAAP]

my new 416 motor, barely broken in, dropped a valve the other day, and bent 2 others. the top of the piston looks trashed, and the head is done for. but the cylinder loooks in OK shape.

im wondering if i could get away with just slapping a new head on, and a new piston set, or if i need to pull the motor, and check anything in the bottom end. if thats the case, and i need a new crank assembly, i checked prices on things, and the cost for me to do it all will be 800$ or so. now i have a motor in mind that i can buy for less than that, that is in good shape that would be a drop in engine, or should i check mine out more?

thanks for all help

[quad9]

check the rod. make sure it is not bent. did the valve fall all the way into the cylinder? or did it just get bent over into the head?

[400exBRAAP]

just the big part of the valve is melted to the piston, it broke where the stem meets the big part, the stem is still in the head, but the head is all wadded up, and so is the top of the piston... but i can just check the rod, buy a new head, and new piston and stuff, and slap it al back together?

[quad9]

well just make sure the rod is good. and might want to check the cam chain. to make sure it did not get stretched.

[blue_ex_rider]

My motor did the samething I had just got it broke in and was riding it and it dropped a valve as describe above. What could cause this to happen I am bout to put mine back together I got a new head and pistion and everyhting is htere anythign I need to watch for or do to be extra careful to make sure this doesnt hapen again cause a 1100 head gets expensive on a man. So any adivce on way this happened would be great. And the valves that were put in dring the rebuild we new oversize valves so I dont know what caused it to snap and stick in the top of teh pistion any ideas.

[witech]

Did you make sure the oversize valves fit in pockets of the piston?