Complaint:
Rich on idle in Carter W1, WA-1, WO, WDO 1-barrel carbs
Possible cause:
Head of low speed jet unsoldered
Worn or too large metering hole in low speed jet
Upper end of low speed jet not sealed in casting
Air bleed or bypass hole in casting restricted with carbon
Economizer in casting too large
Idle port damaged
Gasoline leak at nozzle where it seats in casting
Idle screw damaged so as to prevent adjustment
Carbon around bore where throttle valve seats, causing a rich port opening
Throttle valve installed wrong