RD 520 Chain & Sprocket Conversion Kit

Kit Includes

• Precision-machined steel 520 countershaft sprocket
• Lightweight 520 aluminum rear sprocket
• Premium DID 520 roller chain, manufactured in Japan (or similar depending upon availability)
• Chain cut to the correct length for your specific model
• Note: RD400 models require a shim kit. See product description for info/link
• Gold chain option available

Gear Ratios

RD250 / RD350

• 14-tooth front sprocket
• 39-tooth rear sprocket

RD400 (1976-1978)

• 16-tooth front sprocket
• 39-tooth rear sprocket

RD400F (1979)

• 15-tooth front sprocket
• 37-tooth rear sprocket

These proven combinations represent the most popular street-performance gearing setups for the RD series, providing stronger acceleration and improved throttle response while maintaining excellent rideability.

Lightweight Performance Advantage

Our rear sprockets are manufactured in the USA from premium aircraft-grade aluminum and hard anodized in black for maximum durability and wear resistance. The hard-anodized finish dramatically increases sprocket life, providing longevity that approaches many steel sprockets while retaining the significant weight savings of aluminum.

Compared to a similar steel sprocket, the aluminum rear sprocket weighs less than half as much, reducing both rotational and unsprung weight. Because unsprung weight has a greater impact on suspension performance and handling than weight carried by the chassis, even modest reductions can produce noticeable improvements in acceleration, responsiveness, and overall ride quality.

For example, a stock RD350 steel rear sprocket weighs approximately 2 pounds, while our aluminum sprocket weighs just 12 ounces. That’s a substantial weight reduction in a component that directly affects both suspension action and drivetrain performance. In addition, the 520 roller chain is narrower and consequently lighter (approx. a half pound)

Durable Black Hard-Anodized Finish

Every rear sprocket features a black hard-anodized coating that provides outstanding wear resistance and corrosion protection while maintaining a clean, factory-performance appearance. Other colors available by special order, there is no silver option and the grey just doesn’t look like a natural sprocket and we don’t recommend it.

Important RD400 Note

RD400 C/D/E/F models require sprocket shims for proper chain alignment. An RD400 shim kit is available separately on our website at this link. RD400 520 Conversion Shim Kit (opens new tab)

Quality Components

• Rear sprockets proudly manufactured in the USA
• Premium DID chains manufactured in Japan
• Model-specific chain lengths and gearing
• Proven street-performance ratios
• Reduced rotational and unsprung weight
• Hard-anodized finish for extended service life

Whether you’re rebuilding a vintage RD, Cafe or a high-performance street/race application, this conversion kit delivers the perfect combination of lighter weight, improved acceleration, and long-term durability.