CILOYU 420 High-Speed 40T Minibike Sprocket — 37mm Bore, 420 Chain for CT100U & 212cc+

CILOYU's 420 high-speed 40-tooth sprocket is a direct-fit performance replacement for CT100U-style minibikes, offering a 37mm center bore and hardware kit to boost acceleration and top speed for 212cc+ engines.

This sprocket kit is built for riders who want a reliable, higher-speed final drive for minibikes like the Coleman CT100U, Baja Doodle Bug DB30, and similar 212cc and larger platforms. Machined teeth and precise mounting dimensions deliver smoother chain engagement and reduced wear, while the included accessories make installation straightforward so you can get back on the trail quickly.

How does this sprocket increase speed without sacrificing drive quality?

The 40-tooth 420 sprocket shifts final drive ratio to favor higher road and trail speeds on larger engines. Precision-cut teeth and a compatible 420 chain size maintain efficient power transfer so acceleration remains responsive rather than jerky.

• 40 tooth design for higher top-end velocity on 212cc+ engines
• 420 chain profile reduces friction and improves engagement consistency
• Precision machining lowers chain wear for longer service life

Will this sprocket fit my minibike and what are the exact mounting specs?

This sprocket is specifically sized for many CT100U-style and similar minibikes but is not compatible with 200-series models. Check the center bore and bolt circle before ordering to ensure a correct fit.

• Center hole diameter: 1.46" (37 mm)
• Mounting bolt circle: 1.93" (49 mm) center-to-center
• Overall diameter: 6.50" (165 mm) with 6 mounting holes

What comes in the package and how easy is installation?

The kit includes all necessary hardware and a small sprocket for the engine side, so you won’t need to source extra fasteners. Basic hand tools and moderate mechanical experience are sufficient for most backyard installations.

• Included: 1× 420 40T sprocket and 1× 420 10T sprocket
• Also included: 5× 420 master link, 6× screws, 6× nuts, wrench, 3/16" keyway
• Installation: fits standard 6-bolt patterns; follow torque specs for safe mounting

How durable is the sprocket under off-road use?

The sprocket is designed for rugged minibike and off-road conditions, using hardened tooth profiles and careful machining to resist premature wear. Regular chain maintenance will prolong component life and maintain consistent performance.

• Hardened teeth reduce deformation under load
• Precision tooth spacing minimizes chain stretch and wear
• Compatible with 420 chains commonly used on 212cc and larger engines

Who is this for: CILOYU’s 420 high-speed 40T sprocket is ideal for minibike owners upgrading from stock gearing to a higher-speed setup—particularly those running 212cc or larger single-cylinder engines on Coleman CT100U-style frames, Baja Doodle Bug models, Monster Mega Moto, Motovox, and similar bikes. If you need a direct-fit performance sprocket with included hardware for a quick swap and better top-end, this kit is built to deliver. Note: it is not compatible with 200-series minibikes such as the Coleman CT200U or Axis M200—measure your hub and bolt pattern before purchase to confirm fitment.