The Sunstar 39k-Y45 Rear Sprocket is a high-quality 7075-T6 aluminum sprocket designed for Yamaha motorcycles from 1984 to 1992. Made by Sunstar, a reputable manufacturer known for producing durable and reliable motorcycle parts, this rear sprocket is compatible with the OE/OEM part number 39K-Y45. With a 45-tooth design and 428 chain compatibility, this rear sprocket is a perfect fit for Yamaha YZ80 models, providing durability and performance for your motorcycle. Made in Malaysia, this sprocket ensures top-notch quality and craftsmanship for your riding needs.

* **Condition:** New

* **Brand:** Sunstar

* **Part Number:** 39K-Y45 (39K-Y45-WKS)

* **Position:** Rear

* **Tooth Count:** 45 Teeth

* **Chain Size:** 428 Pitch

* **Material:** Premium Aerospace-Grade Aluminum

* **Country of Manufacture:** Japan

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## Part Number Cross-Reference

Ensure correct application by matching any of the industry-standard interchange numbers below:

* **Sunstar Numeric ID:** 5-249245

* **Yamaha OEM Equivalent:** 39K-25445-01-XX

* **JT Sprockets:** JTR1831.45 / JTR831.45

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## Vehicle Fitment

This sprocket uses a specific bolt-hole pattern engineered for the legacy Yamaha 80cc hub design. It fits the following models:

* **Yamaha YZ80** — 1984

* **Yamaha YZ80** — 1985

* **Yamaha YZ80** — 1986

* **Yamaha YZ80** — 1987

* **Yamaha YZ80** — 1988

* **Yamaha YZ80** — 1989

* **Yamaha YZ80** — 1990

* **Yamaha YZ80** — 1991

* **Yamaha YZ80** — 1992

*Note: Does not fit 1993 and newer YZ80 models, which converted to a different hub configuration (JT Sprocket JTR798 series).*

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## Shipping & Returns

* Fast shipping with tracking provided.