Think i blew the motor?

stu182

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Dec 11, 1999
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#1
Well , rode all day then when i got back to the house figure i rip threw the creek a few times, Went to jump a rock and the throttle stuck wide open, after about 40 foot of hanging on then tying to get away from the bike, I finnaly stopped rolling. The bike was wfo so i hit the kill, no good, jerked the plug, no good, trying to pick a wfo bike up isnt a good idea either, So i pulled the gas line. It finnaly stopped. Trashed bars and triple clamps, and possible blown motor.
Thats the question. There is a knock / clunk when i slowly kick it. I havent tried starting it yet, I'm hearing alot of botom end motor noise. Like maybe something is rubbing but not grinding? Oil was kinda dark tan milk. It kicks over fine doesn't seem to be anything binding up other than the noise. I just got the motor back from 2 fast racing had new bottom and top done. Does it sound like ima have to do it again?
 

dirt bike dave

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May 3, 2000
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#2
I think you absolutely have to at least pull the cylinder off to take a look. My thoughts are that if it was still firing with the kill button pulled in and the ignition wire disconnected, something in the combustion chamber got really hot - hot enough to fire the fuel without any spark to the plug. Not good.

Examine the piston very carefully for damage, and try to figure out what caused the bike to keep igniting. Some sort of metal burr in the combustion chamber or on the piston top could have got super-heated. Possibly jetted too lean. Good luck - IMO you might get lucky, but I'd plan on at least a new piston and rings. Cross your fingers and hope that your oil did its job and protected the main bearings.
 
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Nov 21, 2000
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#3
I have no idea whats wrong with your bike but that is an awesome story!
You must have been frantic to shut it off! I'm going to check my throttle cable right now, just to be safe. Hope nothings hurt bad.(including you).
Steve
 
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Apr 13, 2000
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#4
I seem to remember in the past how C-Dave and some other guys have had the same problem with the throttle pinning WFO. I think it might have been something with an air leak... you might want to drop C-Dave an email.

Dave
 

Mark C.

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#5
I've had past experience with the throttle sticking WFO. It's the worst experience ever! Check the throttle cable an see if it pulls freely now. For the dark tan milky tranny oil I assume water got into your engine ( possibly a blown water pump gasket ) and thats never good :scream: . I would definetly take the topend off and inspect.
 
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Mar 22, 2007
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#6
i have a 1989 ktm it stalled i kicked it one hundred times wouldnt start the when it did start it would run wide open so i press the kill switch and it nothing stilll screaming so i put it in 5 gear dump the clutch and it stilll digs a 2 foot hole in the ground i completly rebuilt the carb checked the cable ever thing still running wide open so a guy told me maby crank seals like it was sucking air up through the bottom of the cylinder but when i was looking at doing that i noticed the head bolts were finger tight and the gasket was poking out so i called every dirt bike shop, checked every website couldnt find any thing on the bike and nobody made a base seal for it i called up the ktm company and they sent me 4 wrong gasket so i made my on but iam almost afraid to start it when goes it goes do you thing thats the promble this has been going on for 3 years. i could not find any thing on this bike like it didnt exist so just wanted what people had to say later
 
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#7
Did 2-Fast kick up the compression alot? Were you too lean also? I think Dirt bike Dave's scenario is plausible. A real hot combustion chamber and highly compressed fuel resulting in runaway dieseling doesn't seem to be all that unlikely. Take the top end off and go thru the cycle a couple times, also check play on big end. good luck.
 

kdxtaz

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#8
So...you rode all day and it ran fine? When you got back to the house and rode it again, did you forget to turn the gas back on? What happened is the bike had a super lean condition, as if it were running out of fuel. Too much air, not enough fuel (or oil) = possible engine damage