so... when I had my nasty crash the throttle got stuck open for a LONG time
well, today I was test fitting shanmans headstay and getting started on putting the bike back together (cleaned airfilter and started putting subframe back on). I moved the kicker over to fit my hand through and then discovered I could push my kicker by hand... I busted out the compression gauge and the results were less than good.
so I tore it apart and lookie at what I found cracks and all
'09 kx450f 4-Poke
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
hey bob what you think of this idea- if the bikes is full throttle laying on its side for 5min half the gas would be running out the overflow hoses and probly only getting half the gas...and danny had that carb with extra small main jet, probly wasnt enough fuel in the bowl for the powerjet. seems like this would be the same as shutting the petcock off and holding it wide open untill the bowl is dry- just before the bowl is empty it gets real lean but will still run
well, my rod bearing is toast and my stator side seal was leaking (which might be why it only seized on that side).
I knew I needed a rod bearing, but now its worse, when I was turning it by pushing the rod it was scraping the cases just a tad. So I split the cases and gutted everything, so now I have a 23lb motor for gen-4 mockup and I got my gen-1 down to the frame. MFDB is gonna bead blast that gen-1 frame for me since I'm not too into the polished look.
I don't know why everyone is always so afraid to split the cases, I got everything torn apart and inspected in about 2 hours. I put the kids to bed and went for it!
'09 kx450f 4-Poke
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
na, I was down for a few seconds, but my kill switch was damaged and the throttle housing crushed in the WOT position. I tried to stall it out, but then it did a few circles around me, then took off. it finally died while on its side spinning itself around in circles. I asumed the bown ran out of fuel, but it looks like a lack of compression is what shut it off!
'09 kx450f 4-Poke
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
well guys, I did that topend in august 2006 and hammered the crap out of it! Its not like it quit because of shitty machine work or a refective piston, I definitly killed it. I honestly couldn't be happier, I got some serious hours on it and it still had no signs of any real blow by! MFDB shitcanned a couple pistons in the time I went through this one. It was really time for a new one anyway, and since it was a .5mm over bore, I have plenty of room. Infact, I also have a spare topend with a 2.00mm over piston that just needs some rings, I might just re ring it for the trail season while I get my ported jug back together.
'09 kx450f 4-Poke
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
looks to me it had more to do with your rod bearing possibly even a bent or slighty twist rod. the crown of the skirt should be square to the big end of the rod or crank. if not the skirt will load to one side in the cyl.and ruinin the piston. every time we mount a piston on a rod weather new or old we put it on the rod aligner to make sure the skirt is square with the rod,hard to do on a 2 smoke but all-in-all sounds like you allready found your problem (bearing)
It was really time for a new one anyway, and since it was a .5mm over bore, I have plenty of room. Infact, I also have a spare topend with a 2.00mm over piston that just needs some rings, I might just re ring it for the trail season while I get my ported jug back together. 
There is never a camera around when the crazy shit happens!
