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Boiling over

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Finally upgraded from 2000 kx125 to a 2000 kx250. This bike is great for what I ride but seems to be boiling over everytime I'm riding it. I noticed Coolant coming out of the overflow even when going to straight stretch where it'd get good airflow.

 

The other day I swapped rad caps from my kx125 to see if there's a difference but it didn't help at all. I ran the bike with the cap off and you can see Coolant moving around showing that the water pump is working.

 

One thing I noticed was after a day of riding and let the bike sit overnight and I'll go check the Coolant the next morning when I pop the rad cap off it'll spay a small amount of coolant from the neck of the rad. It's like the rad is staying pressurized?

 

Any help would be great Thanks!

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Try a new radiator cap . Like a 1.6 . You may also want to make sure you don't have a head gasket leak , have you pulled the plug and made sure it's not wet with antifreeze ? How about running does it smoke extra ? Smell coolant burning ?

 

 

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Head gasket leak is easy as pie to fix. Might as well check it! Just order gasket kit (really just 2 o-rings).

Edited by LSHD
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Try a new radiator cap . Like a 1.6 . You may also want to make sure you don't have a head gasket leak , have you pulled the plug and made sure it's not wet with antifreeze ? How about running does it smoke extra ? Smell coolant burning ?
 
 

Thanks for the replies. I do not think it's burning coolant at all. Smoke is very little and it's blue. Definitely doesn't smell like burning coolant. Spark plug Is a nice brown color. I just changed the coolant today gonna take it for a spin and see what happens.

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Its not uncommon at first for the leak to only go one way.  There is a great deal more pressure in the combustion chamber trying to get out than there is in the water jacket trying to get in.  If it worsens you will see it start to go both directions but you don't want to run it that long.

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This ^^^

 

Not sure why the OP would assume that changing the coolant could possibly solve this problem. EASY to check the head o-rings.

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Alright guys thanks. I'll look into the head gasket sometime this week. I was just trying everything else first Before I went to the head gasket. Something I should add, The coolant that comes out of the overflow is even steaming hot or anything. I can leave it on my finger no problem.

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27 minutes ago, Michael1979 said:

Alright guys thanks. I'll look into the head gasket sometime this week. I was just trying everything else first Before I went to the head gasket. Something I should add, The coolant that comes out of the overflow is even steaming hot or anything. I can leave it on my finger no problem.

Are the radiator hoses very firm when this is occurring?

Purging coolant with no system pressure is a bad cap.  Purging coolant with excessive system pressure and no overheating is a head gasket.

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Are the radiator hoses very firm when this is occurring?
Purging coolant with no system pressure is a bad cap.  Purging coolant with excessive system pressure and no overheating is a head gasket.

Yes coolant lines are warm and firm with pressure. Only time coolant comes out of the overflow is when in the high rpms.
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16 hours ago, Michael1979 said:


Yes coolant lines are warm and firm with pressure. Only time coolant comes out of the overflow is when in the high rpms.

Head gasket

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New head gasket on. No more coolant out the Ober flow. Thanks guys for the help. Here's a pic of my new to me machine IMG_20170515_123350_073.jpg

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