Driven Racing 428 Rear Sprocket for Honda Grom and Monkey 125

$35.99

Driven Racing EVO TECH rear sprocket for Honda Grom and Monkey 125cc with 428 chain.

Driven Honda Grom and Monkey 125 rear sprockets are available in 34t, 35t, 36t, 38t, 39t, and 40t options.

Available in 34, 35, 36, 38, 39, and 40 Tooth
Case Hardened
Fits #428 Chain
Inner Diameter: 58mm
Diagonal Bolt Spacing: 89mm
Made in USA!

Please Note: 2022+ rear sprockets are not interchangeable with 2021 and earlier model Groms. Choose 34t, 35t, or 36t for 2021 and earlier models. Choose 38t, 39t, or 40t for 2022 and newer models.

The stock rear sprocket size on the 2021 and earlier Honda Grom is 34 tooth and you can go up to 35t or 36t to increase your low end acceleration.

The rear sprocket size on the 2022 Grom is 38t and you can go up to 39t or 40t to increase your low end acceleration.

A few rules regarding gear ratios for sprockets are as follows:

Drop teeth on front/add teeth to rear = increased torque, increased acceleration, wheelies, racetracks with short straights
Add tooth on front/reduce teeth on rear = increased top end speed, open road cruising, lowers RPMs, better gas mileage, tracks with long straights
1 down on the front is like adding 3 teeth on the rear
The bigger the rear sprocket, the lower the gearing and the faster the acceleration

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Frequently Asked Questions

When will my order be shipped and how long does delivery take?

Orders containing in-stock items typically ship within 3–5 business days. Orders that include assembly will require 7–10 business days to prepare. Please note that during the holiday season (Thanksgiving through Christmas), processing times may be longer due to high order volume. Once your order has shipped, you’ll receive an email with tracking information. Most orders are shipped via Less Than Truckload (LTL) freight and generally arrive within 3–7 business days. Deliveries to remote areas (such as mountains, forests, valleys, or islands) may take longer. You can check the estimated delivery date on the carrier’s website using the tracking number we provide.

How your vehicle is shipped?

Unless otherwise noted, the vehicles we offer are shipped crated or on a pallet and do not come assembled unless you’ve selected our assembly service. Assembly typically requires a few basic tools and mechanical knowledge. If you're not confident in your ability to safely assemble a high-speed off-road vehicle, we strongly recommend selecting professional assembly or having it assembled by a local mechanic.

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Do you offer financing?

Yes. Buy-now-pay-later financing is available with our preferred partner, BreadPay® (please see their icon under product pricing for details).

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How can I get assistance if I have question on products?

Please call 888-886-5846 and talk to one of our knowledgeable sales representatives between 9am-3pm PST. Or send us email at orders@gokartsusa.biz.

What warranty is included with my purchase?

You're covered with confidence at GoKarts USA®. Your satisfaction is our top priority. Every purchase comes with manufacturer-backed warranty protection—including up to 12 months of engine coverage—to keep your ride running strong. TrailMaster products also include a 6-month parts warranty for added peace of mind.

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What does 95% or 98% Assembly Mean? What do I need to assemble if shipped in crate?

For shipping safety, most vehicles cannot be fully assembled prior to delivery.

Minor assembly is required—this typically includes installing mirrors, connecting the battery, adjusting handlebars, and other small components. Before operation, please ensure all screws and fasteners are tightened, engine fluids are at proper levels, and the battery is fully charged. Your factory warranty remains valid right out of the box.

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Driven Racing 428 Rear Sprocket for Honda Grom and Monkey 125

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