Glen hi,

There are no differences between the Kehin and HRC main jets... They are identical... HRC uses certain numbers that is supposed to be used with open carbs... I don't remember the exact numbers but I think something between 170 to 215...

HRC slow jets comparing them with the MC21 slow jets are longer... But comparing them with the MC28 aren't longer... Are the same...

HRC needles are stamped with a letter A, B, or C... Each letter has a deferent profile...

No, HRC doesn't have a brass ring pressed into the top... HRC needles have five grooves where a clip goes to determine the height of the needles...

Cheers
Michael