RK Racing Chain GB420MXZ-132 Gold 132 Link Heavy Duty MX Chain

In this review the RK Racing Chain GB420MXZ-132 is evaluated for serious motocross riders who demand the lightest, strongest non O-ring option for 50cc to 125cc open class racing. The bottom line: this chain's chrome-moly construction and RK's HIT heat treatment deliver exceptional tensile strength at a low weight, making it the clear choice when strength-to-weight matters most for race use. The review highlights fit, appearance and durability reported by riders, and explains why the chain is aimed at competitive riders rather than casual street use.

Key Features

• Chrome-moly construction: Provides a high strength baseline that keeps the chain stiff and reliable under racing loads.
• Oversized alloy pins: Designed for added shear strength so the chain resists pin failure during aggressive starts and landings.
• HIT heat treatment: All components receive RK's Heat Induction Transfer process to increase hardness and wear resistance across rollers, bushings and pins.
• Lightweight design: At approximately 1.76 lb for this size, the chain reduces rotating mass to help responsiveness on 50cc to 125cc race bikes.
• High tensile rating: The 5000 ft-lb maximum tensile rating gives confidence that the chain stands up to professional level loads.
• Clip master link: Uses a clip-type connecting link for straightforward field service and chain installation.

Who It's For

The GB420MXZ-132 is aimed at competitive motocross and supercross riders, mechanics and teams running 50cc to 125cc open class bikes who need the strongest non O-ring chain in its class. Its combination of a high tensile rating and low weight makes it particularly well suited to riders who prioritize performance and durability in race conditions.

Riders who mainly use street bikes, or casual weekend trail riders who prefer lower maintenance O-ring chains for longer wear life in mixed conditions, may want to consider alternatives. This chain is optimized for race environments rather than low-maintenance commuting or long-distance touring.

Pros & Cons

Pros

• Exceptional strength-to-weight ratio due to chrome-moly parts and HIT heat treatment.
• Durable construction with seamless rollers and bushings that customers note as a solid upgrade over stock chains.
• Gold finish gives a clean, attractive appearance and customers report a precise fit on models like the CRF70F.
• Clip master link allows quick installation and field repairs.

Cons

• Non O-ring design requires more frequent lubrication and maintenance compared with O-ring chains.

Specifications

Model	GB420MXZ-132
Series	420 Series
Tensile Strength	5000 ft-lb
Weight	1.76 lb
Pin Length	15.7 mm
Master Link Type	Clip
Wear Life Index	300

Our Verdict

The GB420MXZ-132 is a strong, lightweight racing chain that offers excellent value for competitive motocross riders who need maximum tensile strength without excess weight. For 50cc to 125cc open class race teams and riders seeking a durable non O-ring chain, it is a sensible buy; riders wanting lower maintenance should consider O-ring options instead.

Frequently Asked Questions

Is this chain suitable for 125cc race bikes?
Yes, the GB420MXZ is designed for professional level 50cc to 125cc open class racing and has a 5000 ft-lb tensile rating appropriate for that range.

Does the chain come with a master link?
The chain uses a clip-type connecting link as the master link for installation and field repairs.

How does maintenance compare to O-ring chains?
As a non O-ring racing chain, it requires more frequent lubrication and inspection than O-ring chains to maximize wear life.