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Old March 15th, 2012, 09:33 PM   #1
RossDickman
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Connecting Rod Bearing Failure?

Hey guys just tore into a 2001 426 yzf yamaha tonight and I thought that the piston was seized in the jug... not the case unfortunately.
Took the jug off and the crankshaft will spin a-okay but the piston is locked on to it tighter than can be... no play what so ever. There is a heat mark on the right side of the crankshaft next to the piston, but I have seen other full, complete, and functioning crankshafts with the exact same spot in the same location. That almost leads me to believing that the heat mark could be from assembly..?

Anyone hear of any similar stories or experience this themselves and know what caused the failure?

Thanks
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Old March 15th, 2012, 09:49 PM   #2
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the bearing is just a needle roller bearing. i have yet to see one with a problem. lets see some pics that your talking about.
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Old March 16th, 2012, 08:24 AM   #3
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The 426 probably doesn't have needle bearings for the piston pin - they usually just float in the piston / rod end and get fed pressurized oil from the crank..

It sounds like it got hot / ran low on oil and seized the pin in the rod. What's weird is that the piston doesn't move on the pin. That's bad. Before replacing the rod, check the price of crankshaft kits: on some bikes a new crank/rod kits with bearings and seals costs less than repairing what you have.
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Old March 16th, 2012, 09:37 AM   #4
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Scooter- yeah ive done some looking around and the average price for a new "used and garunteed satisfactory" is about 300 bucks.

Boggin- Ill snap some later tonight i still need to tare er down all of the way

Thanks for the input gents
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Old March 16th, 2012, 10:22 AM   #5
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Check the price on a new wisco crank with a hot rod.IIRC it was less then $300 for my 250f on thumpertalk.com
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Old March 16th, 2012, 01:52 PM   #6
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Quote:
Originally Posted by bdd1469 View Post
Check the price on a new wisco crank with a hot rod.IIRC it was less then $300 for my 250f on thumpertalk.com
^^^ This is the kind of deal I was talkin' bout! ^^^

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Old March 21st, 2012, 06:08 AM   #7
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Correction* the rod is seized at the crankshaft - not at the piston
Making it a connecting rod bearing failure... Any other ideas? Thanks
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Old March 21st, 2012, 10:36 AM   #8
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Connecting rod kit + labor to replace it.
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Old March 21st, 2012, 10:39 AM   #9
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http://www.motosport.com/dirtbike/oe...NKSHAFT-PISTON
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