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2007 yz 250f engine failure

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I just would like to share what happened to my 15 year old brothers bike.  I am not blaming Yamaha or anything, but my brother. 

 

 

He bought a 2007 yz 250f for $700.  It had a bad crank bearing.  He and my dad spent $900 in parts to rebuild the engine from top to bottom - new cylinder, new crankshaft and bearings, piston, oil pump.  Basically everything except for the head, valve cover, and cases.  When rebuilt, the bike ran great.  I mean, the bike didn't have a problem at all, except maybe it could use some re-jetting as there was a bog somewhere between closed and a quarter throttle. 

 

 

Well, my little brother likes to ride up and down the highways, revving his bike out completely.  He thinks that the rev limiter "sounds cool". 

 

The other day he called me to tell me "his bike just locked up". 

 

got the bike tore down yesterday, and he floated 2 of the valves, destroying the head, and dropping the valves (which shattered) into the piston.  I'll post pics when I get to my phone.  He had been redlining it in spite of our warnings that it would destroy his engine.

 

 

basically, the moral of the story: If you think the rev-limit sounds cool, things get crazy expensive.

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What a fvcking retard. Sorry.. Had to say it.

Haha it's a given.

ImageUploadedByThumper Talk1392569676.301970.jpgImageUploadedByThumper Talk1392569688.859488.jpg

Here are the pictures

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What a fvcking retard. Sorry.. Had to say it.

 

Come on man, the kid is 15.

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So am I.

The thing is, we all warned him countless times to stop doing it or it would be bad.

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He wont do it again, expensive school fees !!

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I would use this as a lesson for him. Assuming i'm his father, I would tell him I spent way to much money for him to abuse the bike in that fashion. I would also remind him of the countless hours spent rebuilding the bike. With summer coming up I would have him start looking for some work, yard work etc., to earn cash to make the repairs. Obviously the kid probably can't recoup that kind of cash but he'll learn to value things he worked and sweat his butt off for. I'd help pay the difference then instruct him on the entire rebuild but make him put in the time and do the work. He's probably going to remember to keep it off the rev limiter after he's spent the last 6 months working on that motor.

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There are timing chain tensioner mods that help prevent this as well but yeah riding the rev limiter is just asking for trouble. Especially on an older bike.

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Stories like this fuel the two stroke vs. four stroke debate. Often the rider blames the manufacturer or four strokes in general. 

 

If he were my kid he would work to earn the 1500-2000$ required for a replacement bike or motor. He would NOT get one from me prior to funds being earned. It may just ruin his whole riding summer but lessons are hard that way. 

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I would use this as a lesson for him. Assuming i'm his father, I would tell him I spent way to much money for him to abuse the bike in that fashion. I would also remind him of the countless hours spent rebuilding the bike. With summer coming up I would have him start looking for some work, yard work etc., to earn cash to make the repairs. Obviously the kid probably can't recoup that kind of cash but he'll learn to value things he worked and sweat his butt off for. I'd help pay the difference then instruct him on the entire rebuild but make him put in the time and do the work. He's probably going to remember to keep it off the rev limiter after he's spent the last 6 months working on that motor.

I know it's late reply. But my dad doesn't have a dime in it. My brother paid 700 for the bike, and 900 in parts to rebuild it. My dad did all the work. But, my dad offered him $250 for the bike. And my brother took it. He has decided he will stick to his utility quad "which just started smoking last week due tj being sunk multiple times and general hard riding"

Maybe one day he will learn. But until then, he's staying far away from my yz450.

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15 year olds are usually douche's, but even at 15, I had respect for mechanical things.

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not everyone is raised the same... my little brother (16) has some loose canon friends i wouldn't trust with a needle in a condom factory. I let mine borrow my truck and my bike from time to time. He even cleans it before handing it back to me. Sure he's fallen scratched it, broken lever, no problem. He also fears i'll kick his a*** if i find abuse. I'm an engine engineer. He knows i'll find out what he did : p

 

thanks for sharing though. that is pretty catastrophic. I love seeing general engine mayhem. Have done the same to a few engines myself. Recently dropped a valve on my M3 track rat. Floated a valve at high rpm or something, valve which kissed piston and embedded itself upside down on the piston crown. Bent two other valves and destroyed a second piston. Fun times. Head was trashed. Similar. Check out eBay for heads there are some refurb deals on there.

 

As for your little brother its time for a life long lesson in appreciating what he has.. plus learning a life-long skill on engines.

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