CDI Unit Assembly – Fits Yamaha Outboard 75HP, 85HP, 90HP (Replaces 688-85540-00-00)
CDI Unit Assembly – Fits Yamaha Outboard 75HP, 85HP, 90HP (Replaces 688-85540-00-00) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
CDI Unit Assembly – Fits Yamaha Outboard 75HP, 85HP, 90HP (Replaces...
Product Details
This CDI Unit Assembly is an aftermarket replacement designed for specific Yamaha Outboard 2-stroke engines, including 75HP, 85HP, and 90HP models manufactured from 1997 to 2000. As a key component of the ignition system, it precisely controls spark timing to ensure reliable engine performance.
It serves as a direct replacement for Yamaha part number 688-85540-00-00 and aftermarket equivalents like WATERLONG 688-85540-00-00.
- Engineered for direct, hassle-free installation.
- Durable plastic housing with metal mounting tabs for secure fitment.
- Controls spark timing for optimal ignition performance.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 688-85540-00-00 |
| WATERLONG | 688-85540-00-00 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | E75MLHY | 75 | 2-Stroke | 2000 | 688-85540-00-00 | Electrical (1) |
| Yamaha | E75MLHW | 75 | 2-Stroke | 1998 | 688-85540-00-00 | Electrical (1) |
| Yamaha | E75MLHX | 75 | 2-Stroke | 1999 | 688-85540-00-00 | Electrical (1) |
| Yamaha | E75MLHV | 75 | 2-Stroke | 1997 | 688-85540-00-00 | Electrical (1) |
| Yamaha | 90ET | 90 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 90TJ series | 90 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | C75, CV75 series | 75 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | C85, CV85 series | 85 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | E75 series | 75 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 75A '06 | 75 | 2-Stroke | 2006 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 75A '07 | 75 | 2-Stroke | 2007 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 75AEHD | 75 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 75AEM | 75 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 75AET | 75 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 85 | 85 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 85A | 85 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 85AE | 85 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | 85AET | 85 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | E75B | 75 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
| Yamaha | E75BMHD | 75 | 2-Stroke | 1984–2000 | 688-85540-00-00 | C.D.I. Unit Assembly |
Technical Specs
- Product Type
- CDI Unit Assembly (Capacitor Discharge Ignition)
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Housing Material
- Plastic with metal mounting tabs
- Dimensions
- 110 × 110 × 35 mm (4.33 × 4.33 × 1.38 in)
- Weight
- 0.45 kg (0.99 lb)
- Other Technical Attributes
- Electronic ignition control module for spark timing
What’s in the Box
- 1 x CDI Unit Assembly (688-85540-00-00)
Installation Notes
- Disconnect the battery terminals to prevent electrical shorts.
- Locate and disconnect the old CDI unit's wiring harness connectors.
- Unbolt and remove the old CDI unit from its mounting position.
- Mount the new CDI unit securely in the same location.
- Reconnect the wiring harness connectors firmly to the new unit.
- Reconnect the battery terminals, starting with the positive lead.
- Test the engine to ensure proper ignition and function.
Troubleshooting & FAQ
How do I know if my CDI unit has failed?
Common symptoms of a faulty CDI include no spark, intermittent spark, engine misfires, rough idling, hard starting, or a complete failure to start. You can test the old unit with a multimeter and compare its resistance values against the service manual's specifications.
Is this part compatible with models outside the 1997–2000 range?
While the core application is listed for 1997–2000 models, our compatibility table shows this part also fits a wider range of Yamaha models from 1984 onwards, and even some specific models from 2006-2007. Always verify your specific engine model and OEM part number before ordering.
What is the main function of the CDI unit?
The Capacitor Discharge Ignition (CDI) unit is the "brain" of your engine's ignition system. It controls when the spark plugs fire, which is critical for engine timing, power, and efficiency.
Can I install this CDI unit myself?
Yes, installation is straightforward for individuals with basic mechanical experience. It involves disconnecting the battery, unplugging the old unit, unbolting it, and then mounting the new one in its place. However, if you are unsure, we recommend consulting a qualified marine mechanic.
What causes a CDI unit to fail?
CDI units can fail due to age, heat, vibration, or moisture intrusion. Electrical issues like a faulty stator or voltage regulator can also damage the CDI box.
Is there any maintenance required for a CDI unit?
CDI units are solid-state electronic components and are generally maintenance-free. The best practice is to ensure all wiring connections are clean, secure, and protected from moisture.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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