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'03 YZ250F goes BOOM !!!!

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This engine is from an '03 YZ250F. The bike had 1 season of riding/racing. The owner is a novice rider and changes the oil regularly. Obviously, the rod let loose. It is now jammed solid between the crank and the case and doesn't look like it can be removed without destroying the case. Of course, many other engine parts are not salvagable. :thumbsup:

240869-P9104817a.JPG

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unlike some that I have seen this engine looks very clean inside.......which would indicate that the oil changes were done. What else would have caused it?

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I'm wondering if it just defective metal, or could it have been ridden hard enough in one season to put that much stress on the rod even with a good maintenance schedule?

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mine looked just like that. perfectly clean . but on mine the rod ripped up the cases. 2 g in parts

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You won't believe the stress that the bottom end has to endure, especially with some one who has a heavy right hand.

I have kept meticulous care of my 01 from day one, and after many hours of harescambles and motocross, something let loose in the bottom end. I figured that it was a crank bearing, but as I split the cases I ended up with half the crankshaft on the floor. The crank split in half at the rod journal. I couldn't believe it.

Want to hear something even crazier? I idled the bike home for about 2 miles like this. Luckily I didn't cause any damage to the case.

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It just hapenned to me 3 days ago. The crank pin has broken in 2 part, My bike is a 01 with approx. 1,500 miles on it, oil change every 150 miles (3 rides)at most and I not too hard on the throttle.

The crank split in half at the rod journal. I couldn't believe it.

I could not too!!!!

My question is did you change the crank bearing. Mine look really good and I rode the bike for about 1 minute with the damage, there was only a little bit of metal in the oil filter, almost like after the break in.

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BOOM, BOOM, BOOM, When my '03 seized the rod bearing I found lots of people having trouble with the '03 crank, I replaced it and thought my troubles were over..... then my '02 did the same thing. I am coming to the conclusion that the YZF250 bottom end is a piece of junk! Hopefully the newer replacement cranks are better designed or stronger. On both of my bikes the engine died for no reason, it would start up right away but die again 5 or 10 min, if you listened real close you could hear the partial seize. I pushed the bike home and only had a crank to replace, if I would have kept on riding HARD my lower end might have looked like the first picture in this post. Just a warning to keep an eye out for the light seize...I got away with $275 in parts.

Jim

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