When XSjohn was developing his needles i bought a set of Mikes Canadian needles 51X11 and needle-jets 336-YO for my BS34's. All i knew was what i had been reading from 650Rider days and assumed our BS34's were the same as the States..................Wrong................When i took my BS34's apart i found the needle jets were the same as Mikes Canadian with 4 and 5 hole 336-YO. and the needles are genuine Mikuni stamped 51X11. They have the adjustable height as well.
I guess the hardest thing is determining if the other jets have ever been changed. I know a set of BS34's i am running have a 30 Main and they have the, (so called), Canadian Needles and Needle jets in them.
XSJohn sent a set of his needles to a club member here, (for trial purposes) and he found they didn't do anything for our carbs, and that would be why
These were not just for the Canadian market, i would hazard a guess they were for the countries that didn't have the environmental restrictions like the States had.
Will post some pics tomorrow