Is my Crankshaft Bad?

100%Honda
I have a CR 125 that just blew up. It somehow ran itself lean and burnt out the piston. It is in very bad shape. The crank seals were just done a couple hours ago. Just looking at the top of the piston makes me think the crank shaft is done, but I'm guessing the previous owner put in a new one because the rod is black. The top of the piston looks jack hammered. I know he did some engine stuff, but I'm not exactly sure what. I was trying find play in the crankshaft, but I don't think there is any.
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CrGuy2T
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CrGuy2T 10/16/2016 12:00pm
10/16/2016 12:00pm Edited Date/Time 10/16/2016 12:01pm
You can get brand new oem 07 cr 125 cranks from Honda of Toledo for like 180.00 main bearings like 55. Be safe than sorry. The 07 crank will fit from 00 and up.
pete24
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pete24 10/16/2016 5:16pm
10/16/2016 5:16pm
if the rod is black there is a good chance the crank is a wiseco, take that junk out rite now

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stevo450
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stevo450 10/16/2016 7:26pm
10/16/2016 7:26pm
That piston has either hit the top of the cylinder or has caught some foreign material...
Picture of crank?
If it is indeed a Wise-co ( not so wise ) then get that junk out!
New oem ones are cheap!
100%Honda 10/17/2016 5:15am
10/17/2016 5:15am Edited Date/Time 10/17/2016 5:17am
Yes from what I have been reading and conversations I have had with other people, wisecos are junk. Like you guys are saying I am going to replace the crank anyways.
Thanks for all the advise! I will keep you posted!
100%Honda 1/16/2017 6:19pm
1/16/2017 6:19pm
I got it rebuilt and running. The exhaust bridge was cracked, but hopefully that won't be an issue. I will post some pictures soon.
MotoX85
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MotoX85 1/17/2017 3:24am
1/17/2017 3:24am Edited Date/Time 1/17/2017 3:27am
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Hondas4Life3
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Hondas4Life3 1/18/2017 12:22pm
1/18/2017 12:22pm
100%Honda wrote:
I got it rebuilt and running. The exhaust bridge was cracked, but hopefully that won't be an issue. I will post some pictures soon.
That is definitely something that needs to be fixed you can't run a cracked cylinder.
100%Honda 1/23/2017 5:21am
1/23/2017 5:21am


I couldn't believe the power difference than from before. I think new reeds really made a big difference! Thanks for all the input!
imoto34
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imoto34 1/23/2017 5:49pm
1/23/2017 5:49pm
bronwynrayne wrote:
You need to fix that crack in the exhaust bridge.
100%Honda, you didn't miss this did you?
100%Honda 1/23/2017 6:54pm
1/23/2017 6:54pm
I didn't miss it. I sanded the bridge down, and tried to make it as smooth as possible. If I ruin a $100 piston, that is cheeper than a $500 cylinder.
Paw Paw 271
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Paw Paw 271 1/23/2017 7:05pm
1/23/2017 7:05pm
You can always send your cylinder off and have it fixed. Fixing the cylinder is much cheaper than fixing your head if it causes you to land on it!

Paw Paw
crobargreg
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crobargreg 1/25/2017 5:07pm
1/25/2017 5:07pm
100%Honda wrote:
I got it rebuilt and running. The exhaust bridge was cracked, but hopefully that won't be an issue. I will post some pictures soon.
I had a cracked exhaust bridge on my cr250. I ended up having the cylinder resleeved. I wouldnt run it like that.

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