Sirris F43 Inverted Front Suspension Fork for Sur-Ron Ultra Bee

Transform your Sur-Ron Ultra Bee into a true off-road monster with the Sirris F43 Inverted Front Suspension Fork. Designed specifically for high-output e-motos, the F43 downscales full-size motocross architecture into a direct plug-and-play assembly. Oversized 43mm hard-chromed steel stanchions paired with seamless 7050 aluminum outer tubes eliminate chassis flex under heavy trail braking and high-speed cornering.

At the core of the F43 is a symmetrical closed-cartridge damper featuring an internal floating piston (IFP) and dual independent oil circuits. By isolating damping fluid from external lubrication oil, the F43 prevents cavitation and heat fade during long, hard rides. Offering 246mm of terrain-devouring wheel travel (standard tune) and an integrated hydraulic bottom-out bump stop, this fork provides maximum control over big jumps, deep ruts, and fast track laps.

Sirris F43 Front Fork Key Performance Highlights

• True Symmetrical Closed-Cartridge Damping: Eliminates aeration and thermal fade for consistent, predictable hydraulic force across long moto sessions.

• Dual Oil Circuit System: Keeps lubrication oil separate from hydraulic damping fluid to maximize oil life and maintain plush small-bump sensitivity.

• 43mm Hard-Chromed Steel Stanchions: Heavy-duty lower tubes resist flex, twisting, and impact damage on harsh terrain.

• Hydraulic Bottom-Out Bump Stop: Ramps up hydraulic resistance near full stroke to cushion heavy landing impacts smoothly.

• Direct Plug-and-Play Fitment: Mounts directly to the Ultra Bee using stock headset bearings, front axle, brake caliper, lower guards, and fairings—no custom adapters required.

• Heavy-Duty 7000-Series Construction: Includes forged 6061-T6 aluminum triple clamps and Type 3 hard-anodized outer tubes for maximum scratch resistance.

 Ultra Bee Factory Tune Configurations

Sirris offers specific valving and spring setups tailored to different terrain, power output, and rider weight:

Rider Weight & Spring Rate Chart

(Weight ranges calculated with standard riding gear included)

 Technical Specifications Matrix

Why Order From Electri Cycle Works?

• Authorized E-Moto Suspension Experts: Consult with our technical staff to choose the right tune (Trail, MX, SX) and spring weight for your riding style.

• Fast Dispatch & Showroom Pickup: Order online for quick freight delivery or select direct pickup at our Salt Lake City showroom.

• Complete Installation Support: Guaranteed compatibility with factory hardware, dashboard mounts, and stock brake setups.

Frequently Asked Questions

Is the Sirris F43 a direct fit for the Sur-Ron Ultra Bee?

Yes! The F43 Ultra Bee fork is a 100% bolt-on replacement. It reuses your stock Ultra Bee wheel, axle, front brake caliper, dashboard display, headlight fairing, and lower leg guards without modification.

What is the difference between Trail Tune and MX Tune?

The Trail Tune offers a softer, more compliant setup designed to absorb rock gardens, roots, and trail chatter. The MX Tune features firmer damping curves and stiffer spring rates to handle large jumps, G-outs, and high-speed track riding.

How often should I service the F43 fork?

Because the closed cartridge separates damping oil from ambient air and lubrication oil, service intervals are longer than open-bath forks. Under regular trail riding, clean and inspect seals seasonally, changing the outer leg bath oil after every 40-50 hours of hard use.