RK Racing Chain GB420MXZ-118 Gold 118 Link Heavy Duty MX Chain

In this review the RK Racing Chain GB420MXZ-118 is evaluated for serious motocross riders who need the lightest, strongest non O-ring chain for 50cc to 125cc open class racing. The bottom line: this chain delivers exceptional tensile strength in a compact, race-ready package, offering a clear performance advantage where durability and low weight matter most. Its combination of chrome-moly construction, oversized alloy pins and RK's HIT heat treatment make the GB420MXZ-118 a practical choice for racers seeking proven strength and longevity without added bulk.

Key Features

• Chrome-moly construction: Provides a strong, fatigue-resistant backbone that holds up under race conditions for dependable power transfer.
• Seamless rollers and bushings: Reduce friction and wear for more consistent performance and longer service life between replacements.
• Oversized special alloy pins: Increase shear strength where chains typically fail, which improves real-world durability on rough tracks.
• HIT heat treatment: RK's Heat Induction Transfer process hardens all components for uniform strength and improved resistance to deformation.
• High tensile rating: The 5000 ft-lb maximum tensile strength gives confidence for professional-level 50cc to 125cc racing applications.
• Lightweight design: At about 1.76 lb the chain minimizes rotating mass, helping acceleration and handling for competitive riders.

Who It's For

The GB420MXZ-118 is aimed at motocross and supercross riders competing on 50cc to 125cc machines who prioritize a race-spec, non O-ring chain that balances minimal weight with maximum strength. It suits riders who swap chains frequently for performance and need a master link clip style for quick installation.

It is less appropriate for casual street bikes or riders who require O-ring lubrication for extended low-maintenance life; those users should consider O-ring or sealed chain options for longer service intervals and different maintenance preferences.

Pros & Cons

Pros

• Exceptional tensile strength and aftermarket durability compared to many stock chains.
• Lightweight construction helps with acceleration on small-displacement race bikes.
• Quality fit and finish; customers report reliable fit on applications like the Honda CRF70F and improved operation over stock chains.
• Gold finish provides corrosion resistance and an attractive race-oriented look.

Cons

• Non O-ring design requires more frequent cleaning and lubrication than sealed chains to maintain wear life.
• Clip master link may be less preferred by riders who favor rivet-style links for a permanent install.

Specifications

Brand	RK Racing Chain
Series	GB420MXZ (420 Series)
Link count	118 links
Maximum tensile	5000 ft-lb
Weight	1.76 lb
Pin length	15.7 mm
Master link type	Clip

Our Verdict

The GB420MXZ-118 is a smart buy for competitive 50cc to 125cc riders who need a race-oriented, light and very strong non O-ring chain. Its chrome-moly parts, oversized pins and HIT treatment deliver a durable, high-performance package that represents strong value for racers willing to perform routine maintenance.

Frequently Asked Questions

Is this chain suitable for 50cc to 125cc racing?
Yes. The chain's 5000 ft-lb tensile rating and lightweight 1.76 lb construction are intended for professional-level 50cc to 125cc open class racing.

What master link does it use?
The GB420MXZ-118 uses a clip-type master link for assembly and service.

Does this chain include heat-treated components?
Yes. All components are heat-treated using RK's HIT (Heat Induction Transfer) process for uniform hardness and wear resistance.