2012 CRF250R blue crank bearings?

garrettcibak71
Edited Date/Time 7/3/2015 8:07pm
Ran out of coolant at my last harescramble and blew out my head gasket. While I had the bike apart, I decided to change the piston. When I took the old piston out I noticed my crank bearings look pretty heated up. Is this okay?

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mx836
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mx836 7/3/2015 11:14am
7/3/2015 11:14am Edited Date/Time 7/3/2015 11:15am
That crank is toast. Way too much heat.
hillbilly
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hillbilly 7/3/2015 11:25am
7/3/2015 11:25am
that is the rod bearing,the crank bearings are in the cases.

you sure the gasket didnt cause the coolant to blow out?

if it got hot enuff to blow that gasket you are going to have other issues.
eeazye
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eeazye 7/3/2015 11:29am
7/3/2015 11:29am
mx836 wrote:
That crank is toast. Way too much heat.
This. You're talking 350+ degrees to discolor steel like that.
Cashmore
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Cashmore 7/3/2015 11:38am
7/3/2015 11:38am
It's probably time to replace the crank...

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TeamGreen
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TeamGreen 7/3/2015 11:50am
7/3/2015 11:50am
Garrett,

This is one of those "while your in there" situations.

A complete Rod Kit from Hot Rods is around $150 and a Complete Bottom End rebuild kit is $550...that's a new crank and all the goods.

If it were mine? I'd send it to CrankWorks.
jsmx97
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jsmx97 7/3/2015 11:55am
7/3/2015 11:55am
A lot of brand new cranks are blued in that area from the assembler heating the crank halves to make truing easier... With that being said, considering your issues, I wouldn't take the risk not replacing it.
MxKing809
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MxKing809 7/3/2015 11:57am
7/3/2015 11:57am Edited Date/Time 7/3/2015 11:59am
SHE GONE!

Also keep an eye out for oil filled smoke out of your crank breather tube. When they get that hot the cylinders can distort and pressurize the crank. On the Kx450' there is a 1" square on the cylinder wall that will concave and produce blow by.... not sure about Honda's though.
Paw Paw 271
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Paw Paw 271 7/3/2015 12:18pm
7/3/2015 12:18pm
Check your cam journals as they take the first hit with over heating or oil issues.

Paw Paw
DTHA70
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DTHA70 7/3/2015 12:55pm
7/3/2015 12:55pm Edited Date/Time 7/3/2015 12:55pm
Paw Paw 271 wrote:
Check your cam journals as they take the first hit with over heating or oil issues.

Paw Paw
its a honda and both ends of the cam use actual bearings instead of a hydraulic roller setup like everyone else. Id be teaing it all the way down and building it. i have seen new cranks with that sort of color from fitting the pin and welding it but its not worth the risk of losing the whole thing if its still together now.
g0rd057
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g0rd057 7/3/2015 4:08pm
7/3/2015 4:08pm Edited Date/Time 7/3/2015 4:16pm
The rod didn't turn blue so it doesn't appear to be an overheated bearing but you won't know for sure until you take it apart and inspect the bearing and journal.
That blue tint in the journal area is probably resulted from the factory process when they made the crank.
Could you hear a rod knock when the engine was running?
BobPA
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BobPA 7/3/2015 4:13pm
7/3/2015 4:13pm
TeamGreen wrote:
Garrett, This is one of those "while your in there" situations. A complete Rod Kit from Hot Rods is around $150 and a Complete Bottom End...
Garrett,

This is one of those "while your in there" situations.

A complete Rod Kit from Hot Rods is around $150 and a Complete Bottom End rebuild kit is $550...that's a new crank and all the goods.

If it were mine? I'd send it to CrankWorks.
+1 on crank works
g0rd057
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g0rd057 7/3/2015 4:17pm
7/3/2015 4:17pm
g0rd057 wrote:
The rod didn't turn blue so it doesn't appear to be an overheated bearing but you won't know for sure until you take it apart and...
The rod didn't turn blue so it doesn't appear to be an overheated bearing but you won't know for sure until you take it apart and inspect the bearing and journal.
That blue tint in the journal area is probably resulted from the factory process when they made the crank.
Could you hear a rod knock when the engine was running?
mx836
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mx836 7/3/2015 4:22pm
7/3/2015 4:22pm
Good call on the color coming from assembly. Didn't think about that.
harescrambled 7/3/2015 8:07pm
7/3/2015 8:07pm
Ya they heat up that area of the crank to make it easier to get the pin in. I never understood it though, because if you heat metal up enough to discolor it, you've changed the mechanical properties of the material, usually making it brittle. And no, 350 degrees isn't enough to turn steel blue. That normally takes about 8-900 degrees. If there is any gray in it, you're talking about 12-1500 degrees.

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