SXR Head Cooling Barb Tap Size

I need an extra cooling line tapped into a 750 head for an SXR. I think it's a JIS / BSTP 1/4-19, but can't find it for sure anywhere. I could just use a 1/4 NPT, but I'd prefer not mix fittings.
 
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Yes 1/8 NPT not 1/4 NPT would be the closest. I'm still pretty sure the stock fittings are something else very close to the 1/8 NPT. I should probably just go with the 1/8 NPT on the new hole and fitting and not worry about it. Thanks
 
People may or may not appreciate this level of detail.

The Kawasaki's use the JIS (Japaneses) standard threads which are interchangeable with the BSPT (British) standard. JIS is very difficult to find so most people will use BSTP which is more available in the US.
While JIS and BSTP are interchangeable they are not identical if you look at their dimensions. The BSPT 1/8-28 is interchangeable with the stock Kawasaki cooling fittings.
I bought a BSTP tap and it lines up perfectly with the stock Kawasaki cooling fitting threads. When you compare it to a 1/8-27 NPT over a distance you can see the threads starting to become misaligned.
I see why people think it's a 1/8-27 NPT, but it isn't. The pitch and diameter are off, but if you can get them started they will go in and work.
For a $5 tap from Amazon I'll stay with the BSTP standard.

 
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