Despite a thorough ultrasonic clean the Mikuni BST 36mm CV carbs on my 1995 Triumph Speed Triple leak fuel from the overflow. The float needles looked OK but perhaps I have missed something? Aaron Follet, email Alan Seeley says: Take another look at those float valve needles. Look out for annular grooves around the tip. If you see any, the needles are shot. Take a look at the float needle valve seats too. It isn’t unknown for these to corrode and if they have you’ll never get them to seal unless you replace them.