Run away bike

What all did you remove and replace? 2 stroke runaways are Normally caused by a lean condition, (majority of the time it’s due to a large air leak)... I’d be concerned about possible damage to your piston...

If the bike set for a long period of time with fuel in the carb while the work was being done, then I would look at a clogged pilot jet. Could also be a hanging throttle cable or sticking carb slide.

Paw Paw

It’s a air leak... check for leaks around the reed cage or motor side of the carb...

Throttle goes all the way down? You have play in the cable?

Im with Paw Paw, throttle cable binding, does the slide snap back after twisting the throttle?

On a snow ride my back in '74 my CZ400 throttle stuck pinned. After trying the kill button, I put her in 4th and jumped on it only to gave the beast launch out from underneath me up the side embankment and fortunately back at me so I could round heal kick it to a rest before it launched into the abyss of the cut block below.
I ripped the plug wire from her jugular only to have the bitch still scream! Finally I shut off the fuel and turned away so not to see the horror play out before me.
Ice packed around a ventricular intake stays very cold.

Omg these are horror stories lmao

Omg that’s fuking horrible

I was thinking about stuck throttles from back in my youth, which was a long time back. I'd guess it was 1973,74 can't remember. Was racing on a track I'd never been to before in Lawton Oklahoma. Was running second and ended up second, some guy on a Yamaha was fast was out front. He as fast between corners, I was faster through the corners. I could never catch him.

Got to the finishline and when I lef off the throttle my trusty CZ just kept going, throttle was stuck about 3/4 open. I ran through the crowd and almost to the parking lot. Only thing saved me was those plastic flags they had strung out to mark the track. I must have had a 50 yards worth of flagging around my sproket. slowed me down enough when I went down didn't hit to hard and throttle unstuck. People were running all over the place it was crazy. Shit happens when you race enough

I actually laughed out loud when i read you claimed to be electrocuted from the kill switch... relax maby you got shocked alittle

I had a run away situation on a recent build. Luckily I was able to pull the clutch in and kill the motor. It wasn't as bad as the horror stories I've read. I did learn a valuable lesson though. Always check the intake boot on 25+ year old bike. I cleaned the Rad Valve intake boot on this 1992 KX250. I never noticed the cracks in it because of the clamp design. You can see easily see the problem with it flexed. New on top....old below.