ATC70 Inverted Fork Conversion Kit – Complete Front Suspension System

A complete front-end system designed to convert your ATC70 from a rigid fork setup to a modern inverted suspension.

This is a fully engineered solution—not a mix of parts. Every component is built to work together to deliver proper fitment, correct geometry, and reliable performance. The result is a front end that installs clean, rides smooth, and holds up under real use.

If you are upgrading an ATC70, this is the complete system to do it right.

System Features

• 45mm inverted fork system for improved rigidity and control
• 540mm fork length for proper stance and geometry
• Adds approximately 1" of front-end height over stock
• Retains compatibility with stock front wheel and spacer setup
• Billet components throughout for strength and durability
• Upgraded steering stem bearing system replaces loose ball design
• Designed as a matched system for correct alignment and fitment

Front-End Design

This system replaces the entire stock front end with a modern suspension setup.

At the center of the system is a precision CNC-machined triple tree, built from 6061 aircraft-grade billet aluminum and finished in a hard anodized titanium gray. Both the upper and lower clamps are sized at 45mm, providing full clamping surface and proper support for inverted fork legs.

The machining quality is immediately apparent—clean edges, tight tolerances, and a finish free of inconsistencies. This is not a cast clamp. It is a true billet component built for strength, alignment, and long-term durability. The stem matches stock ATC70 dimensions for direct fitment, working with either OEM-style bearings or the included upgraded needle-type bearing system.

Torque specifications are engraved directly into the clamp alongside a clean Bart Moto Co. logo, and all hardware is high-quality stainless steel throughout.

Paired with billet 50mm handlebar clamps, the cockpit setup is just as refined as the suspension itself, allowing use of standard 7/8" mini bike handlebars with proper 83mm spacing and positioning.

The 45mm inverted forks provide real damping and control, eliminating the harsh, rigid feel of the factory setup. At 540mm length, the stance stays level with just over an inch of added height—enough to improve function without throwing off the bike’s proportions. The lower fork ends feature billet-machined axle caps with a clean anodized finish for added durability and detail.

A 15mm axle completes the system, designed to retain the stock ATC70 front hub and spacer configuration for a clean, straightforward installation without the need for custom wheel setups.

At the steering stem, the upgraded needle-type bearing system replaces the original loose ball design, providing smoother steering, better load distribution, and increased durability—especially important with a heavier, performance-oriented front end.

The 45mm platform also allows room for future upgrades, including additional fork options and finishes as they become available.

Performance

This conversion completely changes how the ATC70 rides.

Instead of transferring impacts directly into the frame, the suspension absorbs bumps and keeps the front end planted. The result is:

• Smoother ride over rough terrain
• Improved front-end stability
• Reduced flex under load
• More confidence at speed
• Less rider fatigue

Setup

The forks are set up from the factory with a lighter spring rate and lighter fork oil, making them responsive across a wide range of riders.

For a firmer, more controlled feel, preload can be increased internally and a heavier fork oil (around 30W) can be used. We also offer a Pro-Tune option for customers who want the setup dialed in before installation.

Future Ready

This system is built around a modular 45mm platform, allowing for future upgrades as your build evolves.

• Compatibility with upcoming front disc brake systems
• Optional fork guards and protective components (in development)
• Future support for upgraded fork options, including adjustable damping configurations
• Additional finish and color options planned for expanded customization

Fitment

• Honda ATC70 (1978–1985)
• Earlier ATC70 models (K0–K1) compatible with steering stop modification

Important Notes

• Steering stop modification required for early models
• Designed as a complete system
• Professional installation recommended
• Ensure all components are properly torqued during installation