PRODUCT DETAILS
Rectifier for Yamaha Outboards
High-quality marine-grade aftermarket rectifier for selected Yamaha 9.9 HP, 15 HP, 25 HP, 30 HP, 40 HP and 55 HP 2-stroke outboard engines.
Designed as a replacement for Yamaha 664-81970-61 and related rectifier part numbers.
Suitable for selected:
- 9.9 HP – 2 Stroke
- 15 HP – 2 Stroke
- 25 HP – 2 Stroke
- 30 HP – 2 Stroke
- 40 HP – 2 Stroke
- 55 HP – 2 Stroke
CDI/Sierra's application data confirms this rectifier family across these Yamaha horsepower ranges, although the exact applications vary according to model, year and cylinder configuration.
Replaces Yamaha Part Numbers
- 664-81970-60-00
- 664-81970-61
- 664-81970-61-00
- 664-81970-62
- 664-81970-62-00
- 676-81970-00-00
- 6E9-81970-70-00
- 6G1-81970-00-00
- 6G1-81970-60-00
- 6G1-81970-61-00
- 6G1-81970-A0-00
Supersession
664-81970-61-00 → 664-81970-62-00
Yamaha parts data confirms that 664-81970-61-00 has been superseded by 664-81970-62-00.
Fits Selected Yamaha 2-Stroke Outboards
9.9 HP
9.9 HP – 2 Stroke
Selected Yamaha 9.9 HP 2-stroke applications.
CDI lists this rectifier family for selected 9.9 HP 2-cylinder engines, while application catalogues show examples including electric-start models from the early/mid-1990s.
15 HP
15 HP – 2 Stroke
Selected Yamaha 15 HP 2-stroke applications.
Includes selected electric-start and charging-system-equipped models.
25 HP
25 HP – 2 Stroke
Selected Yamaha 25 HP 2-stroke applications, including certain:
- 25
- C25
- CV25
The 664-81970 rectifier family appears across multiple 25 HP generations, so the original part number should be checked before ordering.
30 HP
30 HP – 2 Stroke
Selected Yamaha 30 HP 2-stroke applications, including certain:
- 30
- C30
- CV30
Important
Not every Yamaha 30 HP uses this rectifier.
Yamaha produced different 30 HP engine generations and electrical systems, so please check the original part number.
40 HP
40 HP – 2 Stroke
Selected Yamaha 40 HP 2-stroke applications, including certain:
- C40
- CV40
Again, not every Yamaha 40 HP 2-stroke uses this rectifier.
55 HP
55 HP – 2 Stroke
Selected Yamaha 55 HP 2-stroke applications, including certain:
- C55
- CV55
Application information confirms the 664-81970 rectifier family on selected C55/CV55 engines.
Fitment Summary
| Horsepower | Engine Type | Application |
|---|---|---|
| 9.9 HP | 2 Stroke | Selected models |
| 15 HP | 2 Stroke | Selected models |
| 25 HP | 2 Stroke | Selected models |
| 30 HP | 2 Stroke | Selected models |
| 40 HP | 2 Stroke | Selected models |
| 55 HP | 2 Stroke | Selected models |
⚠️ Please Note
The horsepower list is a fitment guide only.
This does NOT mean every Yamaha 9.9–55 HP 2-stroke uses this rectifier.
The safest method is to identify the original Yamaha rectifier number or check compatibility using the complete engine model and serial number.
Product Features
- Marine-grade aftermarket rectifier
- Suitable for selected Yamaha 2-stroke outboards
- Applications from 9.9 HP to 55 HP
- Replacement for Yamaha 664-81970-61
- Replacement for later 664-81970-62
- Converts charging-system AC output to DC
- Suitable for applicable battery-charging systems
- Direct replacement for compatible applications
- New aftermarket replacement part
Rectifier or Regulator / Rectifier?
I would describe this particular product primarily as a RECTIFIER, rather than calling it a voltage regulator/rectifier.
Yamaha's description for 664-81970-61-00 is “Rectifier Assy”, and the superseding 664-81970-62-00 is also described as a rectifier assembly.
This will also help differentiate this product from the larger regulator/rectifier units you have been listing.
⚠️ Important – Check Before Ordering
Do NOT order this rectifier by horsepower or appearance alone.
Yamaha used different charging systems and electrical components across engines of the same horsepower.
Before purchasing, please check:
- Engine horsepower
- Exact Yamaha model
- 2-stroke engine type
- Engine serial number
- Original rectifier part number
- Electrical connections
- Number and colour of wires
- Mounting arrangement
Ideally, match your original part number.
If the rectifier looks the same as the one fitted to your engine, this does not always mean it is the correct part for your outboard.
If you are unsure, contact SSI Marine with your complete engine model and serial number before ordering.
Additional Cross References
This rectifier family has a particularly large number of cross references.
Yamaha:
664-81970-60-00
664-81970-61-00
664-81970-62-00
676-81970-00-00
6E9-81970-70-00
6G1-81970-00-00
6G1-81970-60-00
6G1-81970-61-00
6G1-81970-A0-00
CDI / Sierra:
157-664-61
Recmar:
REC6G1-81970-62
CDI/Sierra cross-reference information supports these Yamaha numbers and the Recmar replacement reference.
Yamaha-Built Mariner Applications
This rectifier family is also cross-referenced to selected older Yamaha-built Mariner outboards.
Mercury / Mariner references include selected:
- 810937M
- 814995M
- 81652M
- 84329M
- 8M0060278
- 8M0091976
CDI/Sierra identifies selected Yamaha-built Mariner applications from approximately 9.9–40 HP for this rectifier family.
Important
I would not put Mariner in the main product title.
Keep the listing focused on Yamaha, but having these cross references in the description and tags may help customers searching by their existing part number.
Aftermarket Replacement Part
This is a high-quality marine-grade aftermarket replacement part.
It is not a genuine Yamaha component.
OEM manufacturer names and part numbers are provided for identification and compatibility reference only.
The rectifier is designed as a replacement for the applicable Yamaha references listed above.
Important When Replacing a Failed Rectifier
If the original rectifier has failed, we recommend checking the charging system before installing the replacement.
Check:
- Stator output
- Battery condition
- Battery terminals
- Earth / ground connections
- Electrical connectors
- Wiring condition
- Burnt or corroded terminals
Any damaged, overheated or corroded electrical connections should be repaired before fitting the new rectifier.
Buyer Responsibility
It is the buyer's responsibility to confirm that this part is suitable for their particular outboard before installation.
Please check compatibility using your:
- Engine model
- Horsepower
- Serial number
- Original rectifier part number
If you are unsure, contact SSI Marine before ordering. Our technical team will be happy to help identify the correct part.
Why Buy From SSI Marine?
- Marine-grade aftermarket & OEM-spec parts
- Workshop-tested products
- More than 10 years supplying and working with outboard engines
- Same-day dispatch before 1 PM Monday–Friday
- Royal Mail Tracked 24
- UK stock
- Collection available from Leigh, Greater Manchester
- Technical support from experienced outboard specialists
- Workshop open Monday–Friday, 9 AM–5 PM
SHIPPING & DELIVERY
Delivery & Returns Policy
Delivery
Standard Delivery
- £6: Royal Mail Tracked 24 Service
- £3.99: Large Letter - Royal Mail 1st Class Post (Untracked)
We offer free delivery on all orders over £150 (excludes outboard engines).
Orders placed before 1:00 PM (Monday-Friday) are usually dispatched the same working day.
Most parcels are delivered within 24 hours, but please allow extra time for courier delays that may occur outside our control.
For outboard engines, please contact us for a delivery quote.
Important: Please ensure your shipping address is correct before completing checkout. SSI Marine is not responsible for parcels sent to an incorrect address provided by the buyer.
Tracking Your Order
Once your order has been dispatched, you will receive a tracking number via email (after 5 PM on the day of dispatch).
Tracking is available only for parcels sent via Royal Mail Tracked 24.
Large Letter orders are sent via Royal Mail 1st Class Post (untracked).
Returns
We accept returns of unused and undamaged items within 30 days of purchase.
Returned items must be in sellable condition and include the original packaging.
Please do not tape, label, or write directly on the product's original box.
Important: Do not return items in their original product boxes only, they must be placed inside a protective outer box or bag. Parcels returned like the example below will be subject to a 20% restocking fee.
Return shipping costs are the customer's responsibility.
Please include your order details and reason for return inside the parcel.
Refunds
Refunds are issued for the item purchase price only (shipping costs are non-refundable).
All refunds will be made using the same payment method as your original order.
Items returned in poor condition or without proper packaging may incur a 20% restocking fee.
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