650/X-2 Runaway engine

[Scurve]

Just got back from the lake and went to run the engine quick to kick out any left over water when the engine started to runaway...

Caught it all on my dash cam in my truck (well at least the noise)

I let the engine cool down and checked compression... 125 in each cylinder. Engine still turns freely. Hopefully nothing warped from the heat or rpms...

It runs but sounds a bit rough. Turning the engine without the plugs in sounds no different than before.

Where else should I be checking for damage?

Did I get lucky and shut it down before any real damage I wonder...

It ran about 45 seconds WOT(or at whatever crazy rpm it was running off to) without water...

I guess I'll find out next time I get it down to the water :/

edit... original video never loaded

 

[Matt_E]

You might want to find out just why it did that and fix the cause.

 

[Scurve]

Definitely. I'm reading air leaks or air in the fuel lines would do it? It was almost completely out of gas...

It's an old ski and a tired engine. But I just put new gaskets & seals at the beginning of the summer.

Leak down test is in order...

I've also never blocked off the drain plug...

 

[Matt_E]

http://www.x-h2o.com/threads/111672-Runaway-motor

 

[js/sj]

Could be carb to lean also

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[JT_Freeride]

I've had my motor run away when the gas tank was empty. That could have been why but I would still do a leak down test. I hour to test it to make sure everything is correct is way better than rebuilding your engine.

 

[SkiDiggity]

could be a vacuum lead at the carb.. you can always start it up and spray carb cleaner around the base of the carb to see if it will idle and if it takes off stuff a rag in the carb

 

[braden]

Mine did similar but I managed to stop it after about 15 secs. Felt like an eternity. The issue with mine was one of my carbs had a snapped body.

 

[yankeeboy]

for future reference- giving it full throttle would have probably shut it down

 

[DAG]

So you had plug wires flopping around the engine bay and then yanked the fuel lines off? Oh boy, that could have got real fun quick.

Next time hold the stop button down and wide open throttle. It will cut off.

 

[Mark44]

or just hold a rag or your shoe over the exhaust that will kill it.

 

[Dmac80sc]

Damn that went on for a long time!

 

[Myself]

You probably better pull the top end. That went on for a while with no cooling. I bet your rings are blueish and brittle, just waiting to break and wreak havoc next time out. I wouldn't trust it without at least an inspection.

 

[RSKI]

so you had plug wires flopping around the engine bay and then yanked the fuel lines off? Oh boy, that could have got real fun quick.

Next time hold the stop button down and wide open throttle. It will cut off.

x2!

 

[waxhead]

Sounds like it got hot enought to slow the engine down, I bet the pistons were bigger than the bore for a bit there

 

[nightrider05]

or just hold a rag or your shoe over the exhaust that will kill it.

I am amazed I never see anyone mention this. Quickest way to stop a run away.

 

[txsuperjetfreak96]

^^^^^^ yep that's the way I turned the motor off on my nitro rc cars

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[Speleopower]

wow! Not good. Probably time for a rebuild. Isn't 125 compression kinda low? Or maybe should have just ran away and let the engine explode and then rebuild.
wide open throttle to dump cool gas into the cylinder or pump gas in via a primer if you have one, press stop and start switch at the same time and the engine should stop.

Never thought about plugging the exhaust.

 

[nightrider05]

wow! Not good. Probably time for a rebuild. Isn't 125 compression kinda low? Or maybe should have just ran away and let the engine explode and then rebuild.
wide open throttle to dump cool gas into the cylinder or pump gas in via a primer if you have one, press stop and start switch at the same time and the engine should stop.

Never thought about plugging the exhaust.

Yup. Stops it in seconds. And the exhaust really isn't all that hot after going through all the piping and waterbox. I have only had to do it a couple times, but I just used my hands.

 

[Philip Clemmons]

Wow. That was nasty.