YAMAHA EF2000IS INVERTER GENUINE MIKUNI JETS FOR ALTITUDES 4K-7K AND 7K-10K. 
YAMAHA DOES NOT PROVIDE PART NUMBERS FOR THESE JETS
IF YOUR DEPOSITING EXCESS CARBON ON SPARK PLUGS AND IN THE MUFFLER AND SPARK ARRESTOR SCREEN THIS IS WHAT YOU NEED.

OVERALL LENGTH = 6.5 mm
THREAD DIAMETER = 3.9 mm
LARGEST DIAMETER = 4 mm

Due to our remote Location We only ship Fridays and Tuesdays.

Shipping times reflect a 10-day lead time due to the inconsistent service and delivery times currently provided by USPS.  Most items will arrive in 3-7 days but, if you are in an area where USPS is struggling then it may take as long as 21 days to reach you.