The Runaway YZ 125 (What Really Happend)

[@kylepallo9428]

Honestly didn’t know a runaway 2 stroke was possible, learn something new every day. Also good diagnosis!

[@paulbudford]

They can also run backwards! 😲

[@PMBikes-Garage]

Happened on a dt175. Hit the kill switch and still ran for a few seconds. It had a blown head gasket

[@justingreaves6769]

Do leak down test next time mate so you’re not guessing where the leak is 👍

[@bikestardemon]

I can tell you what possibly happened because the bike ran without a plug wire. The plug probably got red hot because the bike had no airflow coming through, the plug being red hot (or hot enough to cause ignition) caused the fuel to still ignite. Of course there is still the possibility of an air leak but i believe my theory is mostly correct because there was no way for it to get spark, and fuel burns once it gets hot enough. Bet the crank seal was part of the problem. heat was the other part.

[@RICHIE_RICH89]

If it didnt have airflow coming threw it wouldnt run at all. This is the most whacled comment ever.

[@RICHIE_RICH89]

No no way if it didnt have oxygen or air coming thru it woukdnt run at all .

[@thenonfarm9575]

Under the circumstances you knew exactly what to do to cut power sources and worked pretty quick to do so. Cudos and thanks for the information so we can all learn from this rare happening...

[@user-pt1hz2wz7h]

I had this issue on my 2001 Suzuki Rm250 2 stroke, ended up being a small hole that developed in the carburetor causing the bike to run so lean it would runway after running for a minute.

[@ryankahl7256]

I had my Honda CR250 Runaway in the driveway a few years back. if it ever happens again just hold both brakes and put it in gear

[@EdFiggs]

Awesome find! Good work man!

[@kennystimac3167]

I had this happen to me on a 2014 KTM250sx. Was an air leak between the power valve o-rings. Absolutely crazy experience. Got messed up pretty bad from it. Trailriding, trees, you know the deal.

[@aidenbell9264]

Hey man I just had this exact issue and I am goin to try this on my 99 yz125, fresh after a rebuild it ran away first start, thanks man

[@jeffdavison8421]

Your cylinder base gasket and intake can cause the same issue if they are leaking. In any event of a runaway condition immediately activate the choke. It will kill the motor.

[@AndrewL-91]

Don’t listen to the hate bud this happen to me like 15 years ago on a tecate 3 wheeler it was sketchy to say the least nothing kills it but lack of fuel or dumping with break locked in high gear but hard to think that fast !

[@lukebridegroom5814]

Great video bud keep it up 👍🏼

[@jasonblair9282]

Crankcase can fill with fuel and run on that when the seal is bad and it’ll run away on ya.

[@mx3sleeper]

Had that happen on a 2 stroke quad. Pulled the plug wire kept going used the clutch in gear to stall it out

[@bushpig6837]

I never knew that was possible. I guess the spark plug becomes a glow plug when it's running that lean, until the float bowl empties.

[@houseofsolomon2440]

Interesting - I learned something today. Really thought only diesel engines could do the runaway thing ~ How did you guys shut it down? Thx in advance -

[@joeshmow1583]

It ran outta fuel

[@bas9528]

i had a runaway 2 stroke aswell, luckily it happend while driving on a long road so i could just simply brake the engine till it stopped running away. Ended up being a worn throttle slide. Letting a lot of air true and causing a very lean mixture, that self ignites.

[@richardcastillo1984]

How about a tools run through video?!

[@MotorMichaelMC]

I would love to make one I got a ton of tools

[@867diesel]

right on dude 🤟🤟

[@luiscotto6659]

My lt250r did this yesterday while getting jetted down was fine till I swapped out a main jet

[@brodybezanilla7180]

Cool

[@knotes76]

Now explain where you are getting that much fuel with your throttle at idle. Just running ultra lean?

[@MotorMichaelMC]

Yep ultra lean. mixes the idle fuel with a excess amount of air and the motor goes to the moon

[@redotsights]

Man my 99 250sx did that shit on me when it ran outta gas it ran away I didn’t know wtf to do lucky just added more gas after it shut itself off and all was well has happened like 3 times all just cause I run outta gas smfh but still same thing started right back up with more gas the second time it happened I ended up just stalling it and that shut it off third time I just forgot to turn my gas on so did that and all was well lol scared the piss outta me🤣

[@FarmerFpv]

Two strokes can runaway and they can run backwards too.

[@jasonluhmer4792]

next time hold the front brake and put it in gear

[@Priidik1524]

Ya should have put it in gear and from wheel against the wall

[@ll.o.r.e1493]

where's the video of the runaway?

[@MotorMichaelMC]

It’s the short on my channel

[@nattydreadlocks1973]

Yes. You may have pulled the spark plug wire, but it was still arking. This is a spark ignition engine.

[@TommyToboggan611]

No when they get hot, they don't need spark to go. The head is hot enough for ignition with no spark.

[@nattydreadlocks1973]

@@TommyToboggan611 Absolutely not.

[@MotorMichaelMC]

@@nattydreadlocks1973look up on google what a runaway 2 stroke is to see how your wrong……

[@nattydreadlocks1973]

@@MotorMichaelMC A two stroke diesel, yes. A two stroke spark ignition, no.

[@MotorMichaelMC]

@@nattydreadlocks1973alright you got it…..

[@ScottSillis]

If the crank seals were leaking it would suck air through there leaning it out, and only run on the fuel left in the carby bowl causing it to rev up until it runs out of fuel. Left it would have stalled itself. Not a true runaway feeding on it's own lubricants. A runaway in a way yes.

[@ScottSillis]

@@MotorMichaelMC I have, but you need to understand what you're saying, I true runaway engine uses the oil as a fuel or uncontrollable fuel supply so it runs to complete destruction, leaking crank seals will cause any two stroke to run lean at a higher rpm just the same as turning the fuel off and running it dry does, the only difference is if you allow it to keep getting fuel from the tank it will run lean until it seizes or runs too lean and stops. If it was running off gearbox oil and fuel different story. This would be the only way a two stroke could be in a true runaway scenario, but call it whatever you want.

[@MotorMichaelMC]

i see what your saying ig but according to google a runaway 2 stroke is when the fuel air mixture ignites itself without the need for a spark plug, witch is what happened here.

[@ScottSillis]

@@MotorMichaelMC the only way I gasoline engine can self ignite is pre-ignition which is usually caused by excessive amounts of carbon burning red hot causing this and extremely rare , this could destroy the engine from detonation and the compression ratio is too low to allow compression ignition, that's why nitro-methanol engines have extremely volatile fuels and use a glow plug to start the ignition process, a two stroke gas engine cannot do that. Does that make sense? Don't believe everything you read on Google man. 🤣 Anyway I'm only trying to help educate you on this phenomena. All good brother, if I'm wrong I apologise, if not your choice if you want to learn from a very experienced person. 👍

[@ScottSillis]

@@MotorMichaelMC runaway from a two-stroke diesel engine is completely different.

[@ScottSillis]

@@MotorMichaelMC if it was caused by carbon then crank seals wouldn't affect the result.

[@michaeljamesdaniel3205]

Carb slide in backwards

[@vilkkiz7397]

just put 6 gear on and stall it or take the spark plug wire off

[@Haze-derr]

Yer u try that and watch the belt u get off it 😂😂😂😂😂

[@wscap4576]

Samething happen to my Yamaha chappy 80cc

[@AndyStossel]

Glow plug too much fuel too quick

[@charleswilson9480]

If they wouldn’t make shit out of plastic these days it would have held up … everything would last longer and work better if they wouldn’t use plastic …

[@BrlU]

how can crank seals trigger runaway motor my mind is blown i cant get around! can you explain it? @MotorMichaelMC

[@MotorMichaelMC]

@@BrlU on a 2 stroke since the fuel mixture is carried throgh the crankcase. If the crankcase develops an air leek it will mix the idle fuel with the air and cause the engine to lean out to the max. The piston will get so hot so fast that the mixture will self combust without spark.

[@robertloftin3910]

So put your foot on rear brake put first gear drop the clutch kill motor