It's an odd size with a fine thread pitch. Aprilia uses the same size. You can get threaded adapters and the other things you will need to sample each cylinder from http://www.bridgeanalyzers.com/900345_moto_desc.php
Not inexpensive and there may be other sourced but this is where I got my stuff. I got the threaded fittings, a length of braided line an NPT fitting to attach the line and a NPT nipple on the other end if the line to attach my gas tester.
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