KAWASAKI 21066-1012 Voltage Regulator KM100 KS125

( Manufacturer Part Number: 21066-1012 ), ( Part Type: Voltage Regulator ), ( Vintage Part: Yes ), ( Country Of Origin: Japan )

Review KAWASAKI Voltage Regulator Reg fits KE100 KE125 KE175 1974-95

The **Kawasaki 21066-1012 Voltage Regulator** is a critical and highly sought-after component designed specifically for Kawasaki s iconic **KE100, KE125, KE175, KM100, and KS125** models produced between **1974 and 1995**. This regulator is a precision-engineered electrical component that plays an essential role in maintaining a stable and consistent voltage output to the motorcycle s electrical system, ensuring reliable performance of the ignition, lighting, and other electrical accessories. Crafted with Kawasaki s signature attention to detail, this regulator is built to withstand the demands of high-performance engines while delivering the precise voltage required typically around **6.0 to 6.5 volts** to prevent overcharging the battery and prolonging its lifespan. The unit features a robust, durable construction with high-quality internal components, including a **rectifier diode assembly** and a **voltage control transistor**, all housed in a compact yet rugged metal casing designed to resist heat and mechanical stress. Whether restoring a classic Kawasaki or maintaining a well-loved vintage bike, this regulator is a **must-have replacement part**, ensuring smooth electrical operation and preventing common issues like flickering lights, weak ignition, or battery drain. Its compatibility with a range of Kawasaki models from the mid-1970s through the mid-1990s makes it a versatile and indispensable upgrade for enthusiasts looking to preserve the authenticity and functionality of their beloved machines.

### **Pros and Cons of Buying a Kawasaki KE100/KE125/KE175/KM100/KS125 Voltage Regulator (1974 1995 Models)**

#### **Pros**

1. **Affordability** These bikes are often sold at low prices due to their age, making them accessible for beginners or collectors on a budget.

2. **Classic Design** The simple, utilitarian styling of these bikes appeals to enthusiasts who appreciate vintage motorcycles, especially those from the early 1970s.

3. **Reliability (When Well-Maintained)** The basic mechanical design is straightforward, and with proper upkeep, they can run reliably for years.

4. **Easy to Modify** The simplicity of these bikes allows for easy customization, such as upgrading the engine, suspension, or exhaust.

5. **Parts Availability** While not as abundant as modern parts, Kawasaki s legacy means that essential components (like the voltage regulator in question) can still be sourced from aftermarket suppliers or salvage yards.

6. **Low Running Costs** Fuel efficiency is decent for their time, and basic maintenance (oil changes, chain adjustments) is inexpensive.

7. **Historical Significance** For collectors, these bikes represent an important era in motorcycle history, particularly in the development of lightweight commuters and racing bikes.

8. **Lightweight & Maneuverable** The small displacement and simple frame make them easy to handle in traffic or on tight roads.

9. **Potential for Restoration** A well-restored example can become a unique, valuable bike, especially if it s rare or in excellent condition.

10. **No Modern Complexity** Unlike modern bikes with electronic fuel injection, ABS, and advanced suspension, these bikes have no complicated systems to fail.

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#### **Cons**

1. **Age & Wear** Most of these bikes are 40 years old, meaning they may have significant rust, worn-out components, or structural fatigue.

2. **Reliability Issues** Without proper maintenance, they can develop leaks, seized engines, or failing electrical systems (e.g., the voltage regulator may need replacement).

3. **Limited Power & Performance** The KE100/KE125/KE175 engines are underpowered by modern standards, making them slow and inefficient compared to contemporary bikes.

4. **Poor Fuel Economy (Modern Standards)** While better than some older bikes, they still consume fuel inefficiently compared to modern commuters.

5. **Safety Concerns** Lack of modern safety features (disc brakes, ABS, frame rigidity) makes them less safe in collisions or high-speed riding.

6. **Electrical Problems** The voltage regulator (part #21066-1012) may be failing, leading to battery drain, dim lights, or no-start conditions. Replacing it can be tricky without proper wiring knowledge.

7. **Resale Value** Unless it s a rare or restored example, these bikes have little to no resale value compared to modern or even mid-2000s bikes.

8. **Environmental & Legal Issues** Some may not meet modern emissions standards, and in certain regions, they may require modifications to be street-legal.

9. **Limited Comfort** Ergonomics are basic, with little suspension travel, making long rides uncomfortable.

10. **Difficulty Finding Skilled Mechanics** Many modern mechanics are unfamiliar with these bikes, making repairs or diagnostics harder.

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### **Conclusion**

- **If you re a collector or enthusiast** who appreciates vintage bikes and is willing to invest time in restoration, this could be a rewarding project.

- **If you need a practical, daily commuter**, a modern bike with better reliability, safety, and efficiency is a far better choice.

- **If you re looking for a budget bike to modify**, these can be fun but require significant work to be roadworthy.

- **If you re buying for parts**, the voltage regulator (or other components) may be worth salvaging, but expect to spend extra on repairs.

The **voltage regulator (21066-1012) is a critical component** if it s failing, replacing it is essential, but sourcing a genuine or compatible aftermarket part may be difficult. A multimeter test can confirm if the regulator is the issue before committing to a purchase.

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### **Recommendation**

- **Do not buy as a daily rider** unless it s in pristine condition and you re prepared for frequent maintenance.

- You re restoring it as a hobby.

- You have mechanical skills and access to parts.

- You re okay with limited power, comfort, and modern safety features.

- **If you need a functional bike**, consider a **modern commuter (e.g., Honda CB300F, Yamaha MT-03, or a used 2010s bike)** for better reliability and safety.

- **If you re buying for parts**, check salvage yards or eBay for the voltage regulator prioritize testing it before purchase.

For most riders today, the **cost of restoration and upkeep outweighs the benefits** of owning a 40 year-old Kawasaki commuter. However, for those with a passion for vintage motorcycles, a well-researched project bike can be a rewarding experience.

Details:

FITMENT: KE100-A10 KE100 1981 KE100-A5 1976 KE100-A6 1977 KE100-A7 1978 KE100-A8 1979 KE100-A9 1980 KE100-B1 1982 KE100-B10 1991 KE100-B11 1992 KE100-B12 1993 KE100-B13 1994 KE100-B14 1995 KE100-B2 1983 KE100-B3 1984 KE100-B4 Canada Only 1985 KE100-B5 1986 KE100-B6 1987 KE100-B7 1988 KE100-B8 1989 KE100-B9 1990 KE125-A10 KE125-A3 KE125-A4 KE125-A5 KE125-A6 KE125-A7 KE125-A8 KE125-A9 KE175-D2 KE175-D3 KE175-D4 KE175-D5 KM100-A1 KM100-A2 KM100-A3 KM100-A3A KM100-A4 KM100-A6 KM100-A7 KS125 1974 KS125-A 1975 1981.

part #: 210661012 prices

• $79.99-$229.99

specifications cyclevintagee:

• for models: Ke100, Ke125, Ke175
• for makes: Kawasaki
• for years: 1974-95
• mpn: 21066-1012
• part type: Voltage Regulator
• vintage part: Yes
• country of origin: Japan

payments cyclevintagee:

• wallet: Apple-pay
• other
• credit card: Discover

returns cyclevintagee:

• paid by: Seller
• policy: Returns Accepted
• time: 30 Days

general cyclevintagee:

• Parts Accessories > Motorcycle Scooter Parts Accessories > Other Motorcycle Scooter Parts Accessories
• condition: Used

offer cyclevintagee:

• availability: In Stock
• started: March 11, 2026
• options: Ship-to-home
• best offers: True
• quantity: 1
• sold: 0

shipping cyclevintagee:

• class: Standard
• cost: $0.00
• transit: 2-6 Days
• type: Calculated
• carrier: USPS
• service: USPS Ground Advantage

seller cyclevintagee:

• city: Spokane, Washington
• rating: 100.0%
• # reviews: 3020

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