CR250 motor damages

Wild_Alaskan · 09-22-2013, 11:49 PM

did a full rebuild on my cr250 and found what made the crunching sound and caused the motor to die temporarily 10 miles out in the middle of no where. I actually put another 5 hours or so on it with the piston like this. still ran ok. Just got a brand new crank and piston

Broken skirt on the intake side and the top ring was stuck by the piece bouncing between the piston and the head. running on one ring and one skirt :P

Weldangrind · 09-23-2013, 01:43 AM

Did you find all of the schrapnel?

Wild_Alaskan · 09-23-2013, 09:41 PM

there wasn't any left, it had all gone out the exhaust, without even damaging the cylinder wall

SpudRider · 09-23-2013, 10:27 PM

That's good luck.

If I were you, I would go buy a lottery ticket as well.

Weldangrind · 09-23-2013, 10:48 PM

I can't figure out how those chunks got to the top side of the piston.

bogieboy · 09-23-2013, 11:23 PM

Quote:

Originally Posted by Weldangrind

I can't figure out how those chunks got to the top side of the piston.

Swept up in the transfer ports?

Wild_Alaskan · 09-23-2013, 11:43 PM

Quote:

Originally Posted by Weldangrind

I can't figure out how those chunks got to the top side of the piston.

Its a two stroke! the crank is separate from the transmission and is part of what pumps the fresh mixture in to the cylinder. The chunk left a nice scratch where it slid between the crank and cases before it made it through one of the ports to the combustion chamber (without getting pinched by the piston) bounced around, sticking the upper ring of the piston by mashing the piston aluminum in to it, then made it out of one of the exhaust ports with out getting pinched again!! like spud said it was very lucky.

In a four stroke there would be no way for it to get out the exhaust, skirts usually end up in transmissions except for bikes like the crf250x where they are separate.

FastDoc · 09-24-2013, 12:35 AM

Its amazing what those older 2 smokes will put up with.

Try the same trick on my YZF and you're out $500 and a weekend of wrenching for sure.

09-22-2013, 11:49 PM	#1
Wild_Alaskan Join Date: Dec 2009 Location: Alaska Posts: 914	CR250 motor damages did a full rebuild on my cr250 and found what made the crunching sound and caused the motor to die temporarily 10 miles out in the middle of no where. I actually put another 5 hours or so on it with the piston like this. still ran ok. Just got a brand new crank and piston Broken skirt on the intake side and the top ring was stuck by the piece bouncing between the piston and the head. running on one ring and one skirt :P __________________ Dune buggy build http://chinariders.net/modules.php?n...wtopic&t=14470 400cc lifan build vid: http://youtu.be/20HoU8OK_Y0 other fun: http://tinyurl.com/wildalaskan
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09-23-2013, 01:43 AM	#2
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Did you find all of the schrapnel? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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09-23-2013, 09:41 PM	#3
Wild_Alaskan Join Date: Dec 2009 Location: Alaska Posts: 914	there wasn't any left, it had all gone out the exhaust, without even damaging the cylinder wall __________________ Dune buggy build http://chinariders.net/modules.php?n...wtopic&t=14470 400cc lifan build vid: http://youtu.be/20HoU8OK_Y0 other fun: http://tinyurl.com/wildalaskan
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09-23-2013, 10:27 PM	#4
SpudRider Join Date: Jul 2008 Location: Idaho Posts: 25,054	That's good luck. If I were you, I would go buy a lottery ticket as well. __________________ Spud "Never argue with an idiot. He will drag you down to his level, and beat you with experience." Mark Twain 2015 Zongshen ZS250GY-3 (RX3) 2006 Zongshen ZS200GY-2 (Sierra 200) 2005 Honda XR650L 2004 Honda CRF250X 1998 Kawasaki KDX220 Mods made to my Zongshen ZS200GY-2: http://www.chinariders.net/showthread.php?t=6894
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09-23-2013, 10:48 PM	#5
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I can't figure out how those chunks got to the top side of the piston. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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09-24-2013, 12:35 AM	#8
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	Its amazing what those older 2 smokes will put up with. Try the same trick on my YZF and you're out $500 and a weekend of wrenching for sure. __________________ Happy to serve.
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