My NC30 (jap) only runs when on reserve,

I presume I need to rebuild the tap but what is the difference between the UK and Jap spec taps?

http://www.nrp-carbs.co.uk/shop/index.p ... ct_id=2898

http://www.nrp-carbs.co.uk/shop/index.p ... ct_id=2897

Am I correct in thinking on the jap spec tap, you can only rebuild half of it?