Radiator caps.

[LEO DPRO 037]

Hey guys, my kx80 has been spitting small amounts of coolant since the day i got it, i topped up every half hour and never fully ran out.
Previous owner put it down to apparent bore work (out to 100cc).
This is the old cap
I baught a new cap and it seems potentially worse? Or at least starts spitting coolant sooner
Is the new one rated at less pressure or more?? They have different numbers relating to different units of measurement on them.

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[china911]

The new cap requires less pressure to open ,so the coolant passes through over flow. it should be stamped on the new cap . press the spring down compared to the old cap. One will have more resistance than the other.

 

[my67xr]

Yeah, The newer one will have a weaker spring.

The problem you have is that you've changed from a 16psi (1.1 Bar) cap down to a 13psi (.9 bAR) cap
So having a 3psi lower pressure in your cooling system will let the coolant boil at 9° lower temperature to, (3° lower for every 1 psi)

The early Kawasaki 2 stroke's run a 1.6 Bar cap (23psi), fitting one of them will solve your problem's.

 

[LEO DPRO 037]

The new one is stamped 13/90 (13psi/90kpa)
Old one is stamped 1.1 but 1.1 bar is 16psi? So therefore dumba$$ here baught a weaker cap... im a spaz!

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[LEO DPRO 037]

Is it at all risky to go to like a 1.3bar to 1.6bar cap?

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[my67xr]

Standard KX80 radiator cap is a 1.6 Bar, anything less and you are lowering the boiling point of your coolant.
I guess if you can only get a 1.3 bar cap, then that's a tiny bit better than the 1.1 you were running

 

[LEO DPRO 037]

1.3 cap made little or no difference. What else should i be looking for? Is my head gasket possibly shot to pieces?

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[my67xr]

Buy an original 1.6 Bar cap, they are expensive from Kawasaki around $50 i've heard
Otherwise your radiator might be blocked and need flushing out at a radiator place

That cap you replaced it with it still 7 psi lower than what it should be.
That mean's the coolant is boiling at 21 degree's lower than it should be, causing a lot more pressure than that 16psi cap can hold.

 

[LEO DPRO 037]

Well i worked out what the problem was. Front of the 4 top head bolts was loose as. Probarbly letting air into the system. Nipped her up tight as i could, 10 minuite ride and not a drop of coolant spitting out .
Thats with my mates 1.3 bar cap, will definately invest in a 1.6 thaugh if that what specs say it should be.
More importantly if craig says it, i agree!!

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[my67xr]

Head stud nut's being loose wouldn't help much either.
Here is the genuine Kawasaki part number if you need it, made by Nippondenso