Main Jet - Genuine Keihin - 99101-ZF5 Type - Sizes #55 to #125

Pick up the main jets that you need for your Keihin carbs here! Genuine Keihin 99101-ZF5.

Sizes Available:

• #55
• #58
• #60
• #75
• #78
• #80
• #82
• #85
• #88
• #92
• #125

Carb Families:

• Keihin FCR / FCR-MX (horizontal and downdraft): used as the slow/pilot air jet
• Kawasaki Keihin CVK/CV on specific road models (below): used as the primary main jet.

Fits the Following Honda Models:

• 2004-2009 CRF250R (FCR-MX 37)
• 2004-2017 CRF250X (FCR-MX 37)
• 2002-2008 CRF450R (FCR 40)
• 2005-2017 CRF450X (FCR 40)

Fits the Following Kawasaki Models: 

• 1980-1983 KZ250 LTD / CSR (Keihin CV32)
• 1981-1982 KZ305 CSR (Keihin CV32)
• 1987-1988 KZ305 CSR Belt (Keihin CV32)
• 1980-1983 KZ440 A/B/D/G (Keihin CV36)
• 1980-1982 KZ750E (Keihin CV34)
• 1980-1983 KZ750H LTD (Keihin CV34)
• 1982-1983 KZ750N Spectre (Keihin CV34)

Fits the Following Suzuki Models:

• 2004-2009 RM-Z250 (FCR-MX 37)
• 2005-2007 RM-Z450 (FCR 40)

Fits the Following Yamaha Models: 

• 2001-2008 YZ250F (FCR-MX 37)
• 2006-2008 YZ450F (FCR-MX 39)
• 2001-2008 WR250F (FCR-MX 37) 
• 2006-2008 WR450F (FCR-MX 39)

Also commonly seen:

• Honda Metropolitan (CHF50) / Ruckus (NPS50) and other small Hondas that use the same Keihin air-jet body for pilot air on FCR conversions or CVK variants.

Does Not Fit List (different jet body):

• Keihin 99101-357 hex mains (CR Specials/FCR fuel mains) — different thread and length.
• Keihin 99101-393 small-round mains (used across many PWK/PE/PD) — different body.
• Mikuni BS/VM/RS carbs.

Notes:

• On FCR/FCR-MX the 99101-ZF5 jet is the slow/pilot air jet in the intake bell (stock is often #100 on MX). It does not replace the fuel main (that’s 99101-357 hex). 
• On the Kawasaki CVK/CV models above - 99101-ZF5 is the primary main jet per Keihin’s own application notes and vendor fitment tables.
• Keihin labels 99101-ZF5 and 99101-124 as the same physical series (3B) - you’ll see both numbers used interchangeably in catalogs.