Honda Grom and Monkey 125 420 Rear Sprocket

420 Rear Sprocket Built for Honda Grom and Monkey 125

This 420 rear sprocket is made to suit the Honda Grom and Monkey 125cc motorcycles, offering a dependable swap-in option for your bike's drive gearing. It is crafted from case-hardened steel, giving it solid wear resistance and strength for everyday riding. It belongs to the group of mini bike & pocket bike parts that can noticeably change how the bike performs and accelerates. Pick the tooth count that corresponds to your model year for the best fit.

How Sprocket Size Changes Performance

Choosing the right sprocket size can make a real difference in how the bike responds. A smaller sprocket tends to boost torque and quickness off the line, which suits short tracks or wheelie practice. A larger sprocket pushes top speed higher, which works well for long highway rides. Honda Grom models built in 2021 and earlier use a 34-tooth sprocket as standard, whereas 2022 and newer models call for a 38-tooth sprocket.

Build Quality and Compatibility

The sprocket is designed to run on a #420 chain and has a 58mm inner diameter and 89mm diagonal bolt spacing. The robust build holds up to both street and track use, so it works well as a replacement for worn or damaged units. Installing it correctly will help the bike run smoothly and efficiently.

Specifications

• Material: Case Hardened Steel
• Size: 34T / 38T
• Fits: Honda Grom 125 and Monkey 125 with 420 chain; 34T for 2021 and earlier, 38T for 2022 and newer
• Inner Diameter: 58mm
• Diagonal Bolt Spacing: 89mm
• Made in: USA

Compatible Models

Fits:

• Honda Grom 125 (2021 and earlier, 34T)
• Honda Grom 125 (2022 and newer, 38T)
• Honda Monkey 125 (420 chain)

Selection guide: Use the 34T version for a Grom from 2021 or earlier, and the 38T version for a 2022 or newer Grom. These two sizes cannot be swapped for one another.

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