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Heat-treated Con Rod? It's blue!

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I blew the base gasket on my '95 XR650L and currently have the top end removed and at the shop for a general refresh... I hope to have it back on the road in a week or two.

 

I've seen a few pics on the forum of XR650L's connecting rod, none of them showed any heat treatment on the connecting rod.  That said though when I opened my engine up this is what I saw:

 

IMG_20140720_210131.jpg

 

The engine's top end has been rebuilt at least once before I got the bike (I'm at least the 3rd owner) so it's a bit of an unknown what was done to the engine by the PO's.  Given the sharp border of the blueing it looks like it was done deliberately.  I always thought that heat-treating a conrod was a big no-no because it makes the metal more brittle and prone to fracturing - shot peening is the way to go.  Should I be worried?  

 

If this wasn't deliberate what would cause the rod to turn that color?  Could the engine have had a major overheating event at some point in the past?  Could an engine overheat ever get hot enough to cause the level of blueing I'm seeing?

 

Would love to hear opinions on this...

 

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I blew the base gasket on my '95 XR650L and currently have the top end removed and at the shop for a general refresh... I hope to have it back on the road in a week or two.

 

I've seen a few pics on the forum of XR650L's connecting rod, none of them showed any heat treatment on the connecting rod.  That said though when I opened my engine up this is what I saw:

 

attachicon.gifIMG_20140720_210131.jpg

 

The engine's top end has been rebuilt at least once before I got the bike (I'm at least the 3rd owner) so it's a bit of an unknown what was done to the engine by the PO's.  Given the sharp border of the blueing it looks like it was done deliberately.  I always thought that heat-treating a conrod was a big no-no because it makes the metal more brittle and prone to fracturing - shot peening is the way to go.  Should I be worried?  

 

If this wasn't deliberate what would cause the rod to turn that color?  Could the engine have had a major overheating event at some point in the past?  Could an engine overheat ever get hot enough to cause the level of blueing I'm seeing?

 

Would love to hear opinions on this...

Perfectly normal....The dis-coloration was caused when they assembled the crankshaft.

 

ME

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All the cranks from the XRL look like that,i`ve seen a pile in my time....as said it`s from heating during trhe press process,,normal..it is NOT a heat treating or hardening process..

 

B

Edited by brianhare

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