GB420MXZ-124 Gold 420 Series Racing Chain - Lightweight Strength

In this review the GB420MXZ-124 is examined from the perspective of a serious motocross rider who needs the lightest, strongest non O-ring chain for 50cc to 125cc open class racing. The bottom line: this chain is built for racers who prioritize tensile strength and low weight, delivering a maximum tensile rating of 5000 ft-lb while weighing only 1.76 pounds, which makes it an obvious choice when durability and race-ready performance matter more than cosmetic features.

Key Features

• Chrome-moly steel construction: Provides a high strength-to-weight ratio that helps reduce rotating mass for quicker throttle response.
• Oversized alloy pins: Extra pin thickness increases shear resistance and extends the chain's service life under racing loads.
• Seamless rollers and bushings: Smooth mating surfaces reduce internal wear and contribute to consistent performance over time.
• RK HIT heat treatment: Heat Induction Transfer hardening gives uniform toughness to components, improving fatigue life in harsh conditions.
• Non O-ring design: Eliminates O-ring drag and lowers weight, making this chain preferable for competitive motocross use.
• High tensile rating: A 5000 ft-lb maximum tensile strength supports professional-level abuse in 50cc to 125cc classes.

Who It's For

The GB420MXZ-124 is aimed at motocross racers and serious off-road riders who race 50cc to 125cc bikes and need a chain that combines minimal weight with maximum tensile strength. Riders who demand consistent lap-after-lap performance and who perform regular maintenance will appreciate the aggressive engineering behind this chain.

It is not intended for riders who prefer low-maintenance O-ring chains for street or trail use, or for those who need corrosion resistance as a primary factor; this is a race-oriented, non O-ring chain best used where performance outweighs cosmetic maintenance concerns.

Pros & Cons

Pros

• Exceptional strength-to-weight ratio that benefits throttle response and durability under racing loads.
• Robust construction with seamless rollers, bushings, and oversized pins offers extended wear life.
• Heat-treated components using RK's HIT process provide consistent toughness and fatigue resistance.

Cons

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

Specifications

Our Verdict

The GB420MXZ-124 is a race-focused chain that delivers industry-leading tensile strength and very low weight, making it an excellent value for competitive 50cc to 125cc riders who maintain their equipment. If you prioritize performance, durability under high loads, and reduced rotating mass, this chain is a solid buy; those seeking sealed, low-maintenance chains for street use should look elsewhere.

Frequently Asked Questions

Is this chain suitable for 125cc motocross bikes?
Yes. The GB420MXZ-124 is specified for professional level 50cc to 125cc open class racing and is built to handle that power range.

What type of master link does it use?
The chain uses a clip style master link for installation and removal.

How does the weight compare to other race chains?
At about 1.76 lb, the chain is notably light for its strength class, improving rotating mass and throttle response for racing applications.