Valve head stuck in piston = bad!!

[darwood300ex]

So I have a 2004 300ex with exhaust intake and cdi box. We went to the track way down in southeast oklahoma this weekend and I got to watch everyone ride all day. Bike died, felt like it had no compression. felt alot like the plug fouled so I went to change it and my bike still wouldn't start. found that the carb had seperated from the boot, fixed that and still no start and felt like compression was still low. got hooked up to my buddies ltr 450 and pulled for a few times. first couple of times it sounded like it wanted to run but as soon as we stopped rolling it died. on the third try, started the same but while my engine was revved up it started knocking very very bad. luckily the guy who ran the track had a shop nearby so we proceeded to tear the head off. turns out the motor floated an intake valve(one of the clips that hold the valve stem into the springs(cotter I believe) popped out, broke the head of the valve off and literally stuck into the piston. holy crap... it also scarred up the head but not on any of the valve seats.

so in sequence here is what I think happened.

1. valves were already chattering so that didn't help.
2. carb seperated from boot and allowed way to much flow and free revving causing the plug to foul.
3. free revving also caused the "cotter" clip to pop off floating the valve
4. valve finally dropped into motor far enough to bend and snap the head off into the piston
5. trying to start with valve head stuck in piston caused the damage to the head.

questions.

1. even though the piston suffered a gouge, can you shave it down or smooth it out and continue using?
2. can I still use this head if i smooth out the gouges and turn the valve seat on the seat that was damaged?

expert replies only on the questions please. dont want to cause further damage.

thank you so much for reading and please always adjust your valves regularly to avoid a situation like this.

[soyo]

sound kinda like the timing chain. it stretched passed its limits and jumped time!

i would just rebuild and bore the cylinder if needed. get a new piston and rings. and timing chain

as far as the head, you can reuse it if the valve seats are still good(no damage) make sure the guides are still good as well! it would be a good idea if you took the head to a machine shop and do a valve job with the new valves. they can inspect it and tell you if its reusable. the cotter key could've poped off when the valve hit the piston also.

[darwood300ex]

took it to a rebuild shop today. nogo. the piston was shot and he said he could resurface the head for about as much as I could get a good used one anyway. thanks for the input

[soyo]

post a picture and we'll see! it could be fixable!

[Black300Ex]

This exact same thing happened to my buddy. What we found out is that it was the timing chain that caused the whole problem. He ended up breaking the timing chain, valve head off in the top of the piston, and ruining the cam. cost about $1200 by the time he was all said and done.

[darwood300ex]

ya i have heard about that. but this was not the case. the timing chain was still connected and marks lined up so it didn't skip time. not really sure what caused the clip to pop off but i think that caused everything. maybe it was because the valves prob had never been adjusted. I have only had the bike for about 1 month and ridden only 5 or so times.

[darwood300ex]

well I got my new top end from a member on here and I'm back in business. I'll try to put some pics up on here to show you guys. It was pretty freakin amazing how it all looked. wont be any pics of the head though. I already ground it back down to a managable spare head state. thats nice having a spare now.