Starter Motor for Kawasaki STX-12F STX-15F STX 160 | 21163-3721

Product Overview

Restore reliable starting performance to your Kawasaki personal watercraft with this 12V electric starter motor, designed for compatible STX-12F, STX-15F, and STX 160-series Jet Ski models.

Featuring a 9-tooth drive gear, counterclockwise rotation, 2.7 Nm rated torque, and a 10,500-cycle rating, this starter motor helps provide fast and consistent engine cranking when the original unit becomes weak, slow, intermittent, or unable to start the engine.

The durable metal construction and wear-resistant internal components are designed to withstand repeated starting cycles and demanding marine operating conditions. Its direct-replacement configuration helps simplify installation when the OEM number, mounting diameter, drive gear, terminal position, and overall dimensions match the original starter.

Product Compatibility

Brand	Model	Model Code / Platform	Year Range	Engine
Kawasaki	Jet Ski STX-12F	JT1200B / JT1200D	2003–2007	1199cc
Kawasaki	Jet Ski STX-15F	JT1500A	2004–2019	1498cc
Kawasaki	Jet Ski STX 160	JT1500R	2020–2022	1498cc
Kawasaki	Jet Ski STX 160X	JT1500S	2020–2022	1498cc
Kawasaki	Jet Ski STX 160LX	JT1500T	2020–2022	1498cc

Kawasaki’s official parts diagrams list 21163-3720 for the 2003 STX-12F and 2004 STX-15F. Later STX-12F and STX-15F diagrams list 21163-3721, including the 2007 STX-12F and 2019 STX-15F. The 2022 STX 160LX also uses 21163-3721.

The STX-15F model name should not be extended through 2022. For 2020–2022 applications, the applicable model names are STX 160, STX 160X, and STX 160LX.

OEM Cross-Reference Numbers

Kawasaki

• 21163-3720
• 211633720
• 21163-3721
• 211633721

Common Aftermarket Cross References

• Lester/WAI: 18432
• Lester/WAI: 18432N
• SBT: 503SB213

Kawasaki OEM number 21163-3721 supersedes or replaces the earlier 21163-3720 starter number.

Your original starter does not need to display every number listed above. However, at least one compatible OEM or interchange number should match the original unit or the official parts catalog for your watercraft.

Specifications

Specification	Details
Product Type	Electric Starter Motor
Voltage	12V
Drive Gear	9 Teeth
Rotation	CCW / Counterclockwise
Rated Torque	2.7 Nm
Cycle Rating	10,500 Cycles
Overall Length	189 mm / 7.44 in
Mounting / Insertion Diameter	45 mm / 1.77 in
Fitment Type	Direct Replacement
Vehicle Type	Personal Watercraft / Jet Ski
Housing Material	Metal
Condition	New
Package Quantity	1 Starter Motor

Rotation descriptions may vary depending on which end of the starter is viewed. Confirm compatibility using the OEM number, tooth count, drive-end shape, mounting diameter, terminal position, overall dimensions, and product photos.

Measurements may vary slightly depending on the measuring method. Compare the same measurement points shown in the product images with your original starter.

Key Features

• Broad Kawasaki PWC Fitment: Designed for compatible STX-12F, STX-15F, and STX 160-series personal watercraft.
• 12V 9-Tooth Configuration: Features a 9-tooth drive gear and counterclockwise rotation for compatible Kawasaki starting systems.
• Strong Cranking Performance: Rated at 2.7 Nm to help provide fast and consistent engine startup.
• Durable Construction: Wear-resistant internal components help support dependable operation under demanding marine conditions.
• Direct-Replacement Design: Matches the original-style mounting and electrical configuration when all specifications are correct.