Bubbles in the radiator

[yz250-ridercro]

Is this normal or not??
I put the overflow tube from the radiator in water with the radiator cap on and there are no bubbles so i think its not the head gasket!!
Can the impeller make bubbles?

Thanks

 

[BSWIFT]

If your radiator pressure was high enough, you would get some coolant out of the overflow(the cap is designed to release excess pressure). Check your oil and see if it has a milky color. I wouldn't rule out the head gasket based on your first test.

 

[oldguy]

Start the bike with the radiator cap off and if you see bubles chances are the head gasket is leaking. The impeller should not cause bubbles

 

[yz250-ridercro]

I can see bubbles with the radiator cap off but I just had my top end done and replace all gaskets!!!
The motor runs great so i don't know what to do!!
If the head is leaking in the coolant has to be some oil or gas but I don't see nothing!!
Can you take your radiator cap off and see do you have some foam when your engine is running???

 

[whenfoxforks-ruled]

Check your plug. Black and wet, trying to burn antifreeze. Take the cap off the radiator, start it and watch, do the bubbles increase with rpm? Get a compression tester and test the top end. Last week, some guy with the same issues as you. He found out the importance of a torque wrench.

 

[oldguy]

There is a good chance nothing is getting sucked into the cylinder just pressure blowing out of it. If the jug bolts were not properly torqued or the base is warped then the new topend would not cure it. From your description you now have at least a bad head gasket

 

[yz250-ridercro]

So with a compression tester I could see if I have a head gasket leak??
What is normal compression of a cold engine??