If fuel is overflowing the float bowl the needle valve is leaking. This may be caused by the float being misadjusted, stuck or leaking OR the needle may be fouled with a bit of grit or worn and not sealing. This is an

alternative updated version with brass/bronze rod which flows and wears better. 

Fits HS2,HS4 and HS6 carbs but not HIF range. CA90 is ethanol tolerant