Big Bore Destruction! What are my options?

[AutoRoc]

Short story: Bought 440EX, rode 440EX, killed 440EX with possible over-rev or over-heat in the dunes.

Tore it down tonight. Both intake valves were IMBEDDED upside down in the piston. Hole in piston. Bore looks good still oddly enough. Head damage obviously.

What would you guys do? I'm assuming the bottom end is good still but I didn't plan on diving into the lower end until seeing this much damage. There has to be metal in the lower with the holed piston.

Share some thoughts. yank it and send it to a reputable builder? Who would you pick? Find an ebay deal for replacement?

Originally posted by AutoRoc
Both intake valves were IMBEDDED upside down in the piston. Hole in piston. There has to be metal in the lower with the holed piston.

that right there happened to my brothers 400ex with a stock bore, the timing was a little off and the piston hit the valves broke them, then when it went up again sent the valves through the piston and melted them in.

[Pojo450r]

talk to chad502ex he knows what he is doin

[Pipeless416]

Originally posted by AutoRoc
Short story: Bought 440EX, rode 440EX, killed 440EX with possible over-rev or over-heat in the dunes.

Tore it down tonight. Both intake valves were IMBEDDED upside down in the piston. Hole in piston. Bore looks good still oddly enough. Head damage obviously.

What would you guys do? I'm assuming the bottom end is good still but I didn't plan on diving into the lower end until seeing this much damage. There has to be metal in the lower with the holed piston.

Share some thoughts. yank it and send it to a reputable builder? Who would you pick? Find an ebay deal for replacement?

first things first.. we need pictures:devil:

[gcart2]

x2

[EX LONERIDER]

if top parts and lower parts collided... i would also assume rod is bent.... possibly even crank damage.... id have all that inspected before even touching the top stuff.

[NacsMXer]

Originally posted by AutoRoc
Short story: Bought 440EX, rode 440EX, killed 440EX with possible over-rev or over-heat in the dunes.

Tore it down tonight. Both intake valves were IMBEDDED upside down in the piston. Hole in piston. Bore looks good still oddly enough. Head damage obviously.

What would you guys do? I'm assuming the bottom end is good still but I didn't plan on diving into the lower end until seeing this much damage. There has to be metal in the lower with the holed piston.

Share some thoughts. yank it and send it to a reputable builder? Who would you pick? Find an ebay deal for replacement?

My old 440 setup blew up similarly. I was hitting this 75 ft uphill step up numerous times 4th pinned. On my way up I was in the gas hard then my motor made this crazy loud fluttering sound and died. I ended up seizing both intake valves in the head which allowed the piston to kiss/bend them. When I tore it down the bore looked just fine like you described. Turns out my motor was low on oil and I starved/overheated the head. I built that 440, but after it blew I just said screw it and sent it to GT Thunder for a complete transformation (details in my sig).

If the bottom end is in good shape you could probably just find a head and all the other parts on ebay and try to rebuild. My cylinder "appeared" to be in good shape but Laz called me up and told me it was slightly warped from heat. It's the detailed teardown/inspection that really benefits you when you send your motor off to a professional. Anytime you have chunks of metal floating around in your engine, you're going to want to do a complete teardown/inspection.

It's a tough call as to what you did or did not damage, that all has to do with what caused your problem in the first place. I would try to figure that out before you get it back together.

[AutoRoc]

Thanks guys, I'll get pics eventually...it's ugly.

Pulling it all apart as we speak.

BTW, It happened after doing doughnuts and literally writing words in the sand with a LOT of tirespeed. Definately forgot this thing was air-cooled while having so much fun.