My Account
Shopping Cart

Shopping Cart

0 items in your Cart
View Cart
Subtotal
Track
My Order

Sierra 18-6421 Outboard Starter Motor for Yamaha Outboard Motors

Manufacturer

Picture for manufacturer Sierra

Part Number

18-6421
11 reviews
Sale Price

$270.20

3 left at this price

delivery box

Usually delivered within 2 days

free shipping

FREE SHIPPING

Check out with

ApplePay
Authorize Seller Badge
No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The Sierra 18-6421 is a direct-replacement outboard starter motor engineered for select Yamaha 2-stroke outboard engines ranging from 25 HP to 50 HP. Designed to meet or exceed the performance of the original equipment starter it replaces, this unit is a reliable solution for restoring dependable engine cranking power to aging or failed starting systems.

This starter features an 11-tooth drive gear and induction-hardened motor shaft bearing surfaces for long-lasting wear resistance in demanding marine environments. Sierra's outboard starters are quality-tested to ensure proper performance and meet international marine standards.

Key Features:

  • 11-tooth drive gear for proper mesh with Yamaha flywheel ring gear
  • Induction-hardened motor shaft bearing surfaces for superior wear resistance
  • Meets or exceeds OEM performance standards
  • Built to withstand harsh marine operating conditions
  • Direct bolt-on replacement — no modification required

Replaces Yamaha OEM Part Numbers:

  • 6F5-81800-10-00
  • 6F5-81800-11-00
  • 6J4-81800-00-00
  • 6J4-81800-01-00

Cross-Reference Part Numbers:

  • Arco: 3423
  • Hitachi: S108-87A
  • Mallory: 9-15050

Products specifications

Compatibility

Fits 25HP (19992001)30HP (1996-992001)40HP (1992-03) C40 1997-02P40 (1998)50 (1992-9720002002-03) C50 (1998-01)P50 (1993-96). Replaces 6F5-81800-11-00 SS 6J4.

Type

Starters

very satisfied

Above Average

Great pricing and ship rates, name brand items. Very impressed. Would definitely buy again.

Just hoping this is universal. It didn't say left or right. I need drivers side. Thank you.

Awesome

Perfect!

easy website to use and order

Great Site! looks like you're beating Amazon;)

Great price! Quick shipping. The intake I ordered was $20.00 cheaper than anywhere else I looked. Item was instock and shipped quick. Will order from Autoplicity again!

Liked the amazon pay

easy to use

Share icon
Return Policy
Returns are easy at Boatplicity

Not happy with a purchase? No problem. We've made returning items as easy as possible. And most purchases can be returned for free for 30 days. Learn more about our Returns Policy