Run Away blaster? Plus video HelP!

[Liftaxel]

So I ran my blaster yesterday. Freshly rebuilt top end. Its been broken in. I ran it at super low rpms for 15-20 minutes. Then ran it through the gears, it ran just fine just a little bit rich so I took it to the barn to lean it out. I was just about to lean it out then... It went to idle rpms to full out rpms. I quickly pulled off the coil wire it Was still screaming.. Then pulled the gas line STILL screaming. So I watched it scream its self to death.

It had to create a hot spot on the piston.
Its not seized.
It has 120 PSI.
It did blow transmission oil out the vent.

What would cause this air leak? carb?

Watch the video:

 

[Awk08]

read, learn, follow exactly all the pinned sticky threads.........

http://www.blasterforum.com/forums/carburetor.138/

leakdown test....
http://www.blasterforum.com/threads/build-and-use-a-leakdown-tester.10663/

http://www.blasterforum.com/threads/videos-on-how-to-perform-a-air-leakdown-test.31464/

to prevent this .......

if that happens again, hold the brakes and let the clutch out in gear to stall it.
do not allow it to just run away

 

[armyboyjared]

u can also starve its air supply if your able to rip the carb intake boot off fast enough and plug it with ur hand..but awks suggestion would be much quicker.

 

[warmeck]

shes mad at you cuz shes leaking somewhere and she wants you to fix her asap.

 

[bansheedave]

if that ever happens again, give it full throttle. it will kill it. I had that happen a long time ago. hope you didn't melt the top end together. if not, your lucky. if its still good, leak test it.

 

[bansheedave]

read, learn, follow exactly all the pinned sticky threads.........

http://www.blasterforum.com/forums/carburetor.138/

leakdown test....
http://www.blasterforum.com/threads/build-and-use-a-leakdown-tester.10663/

http://www.blasterforum.com/threads/videos-on-how-to-perform-a-air-leakdown-test.31464/

to prevent this .......

if that happens again, hold the brakes and let the clutch out in gear to stall it.
do not allow it to just run away

this works also

 

[Blaaster]

Blowing oil from the transmission vent tells me that the crankshaft oil seal has crapped its self, or was not installed correctly.

 

[speedyslyder]

that is crazy, wow,must have been one heck of a flame in there

 

[Blaaster]

Were you fooled by excessive smoke that it was running rich, when really the seal was leaking creating a lean mix that fried the piston.

Did you leak test the engine before starting it, if not you have learned a valuable lesson that leak testing after re- building is a must.

 

[Larry's Shee]

I see no mention of
leaktest
heat cycles
re-torque

My thought is it started running lean, which heated the plug to the point the ground electrode was glowing red hot, which acted just like a glo plug in an RC car. Auto ignition

 

[speedyslyder]

bump for anthony21 lol