For those electric dirt bike riders looking to upgrade their Surron Ultra Bee with a direct bolt-on, no-fuss fork, Sirris offers the solution with its F43 fork.
This is the new updated version of the Sirris F43 fork, with 260mm of travel and tool free adjustment!
Note: This listing is for the Motocross (MX) Tune. If you are a Trail Rider, please see the Sirris F43 Trail Tune Fork here.
The Sirris F43 fork is purpose-tuned, pressure-balanced, and offers 10.24 inches of ultra-plush travel. This is the absolute best suspension for your Surron Ultra Bee and will completely transform your bike into a true proper dirt bike that can perform in any terrain.
The F43 is designed with aggressive riding in mind and tuned to your exact riding style and weight!
Now with 260mm of travel, tool-free low-speed compression adjustment, Torx fasteners, and new graphics. MX Tune is purpose-built for motocross performance. Its race-focused setup delivers the balance, control, and bottoming resistance needed to charge through big jumps, hammer whoops, and attack fast corners at race pace.
Want to see all of the Sirris Fork & Shock Options? Click here every Sirris Suspension tune we sell.
Here are some highlights:
Plug & Play Installation: The F43 fork seamlessly integrates with the Surron Ultra Bee’s OEM front-end setup, with factory compatibility with the OEM display, fender, and brake caliper. This is a direct swap for the stock Ultra Bee, with a pre-installed dust seal and headset bearing. Designed to fit directly with the Ultra Bee fairing and cable routing. No additional modifications are required.
Enhanced Front End: 43mm stanchions and robust upper fork tubes provide significant improvement in stability and strength while maintaining the bike’s turning radius.
Increased Travel: 10.24 inches (260mm) of travel, offering extra cushioning, which is particularly beneficial for aggressive riding.
Hydraulic Bump Stop: Smoothly handles even the most forceful impacts at maximum stroke, providing progressive bottom-out control and softer landings.
True Symmetrical Closed Cartridge: Ensures balanced load distribution and consistent performance, resistant to fade for predictable handling after extensive use. No matter how hard you ride or how many laps you take, Sirris closed-cartridge forks deliver consistent, fade-resistant performance.
Dual Oil Circuits: Separate lubrication and damping oils optimize damping performance without compromise.
High-Quality Materials: Made from 7000 series aluminum with Type 3 hard anodizing for strength and scratch resistance. Hard chrome stanchions, NOK Heavy Duty seals, custom Daido bushings, and wrap-around guards extend performance lifespan.
Ultimate Suspension Tuning: Fully tunable valving for compression and rebound, with spring rates matched to your weight and riding style for a tailored suspension setup.
Updated Adjusters: Tool-free low-speed compression adjustment makes trailside changes simple, while rebound uses a tool-operated adjuster for durability in harsh environments.
Lightweight: Each leg weighs only 8.8 lbs (4 kg), offering a powerful yet lightweight upgrade.
Sirris offers five weight ranges to choose from when selecting your MX Tune F43 fork. Listed weight ranges are rider weight without riding gear. An additional 15 pounds of riding gear is already calculated into the weight ranges.
Rider Weight Without Gear
Spring Option
Springs — Left / Right
Under 160 lbs
Light
4.4 / 4.4
160–200 lbs
Medium
5.0 / 4.8
200–240 lbs
Heavy
5.4 / 5.0
240–280 lbs
X Heavy
5.4 / 5.4
Over 280 lbs
XX Heavy
5.4 / 5.4
Pair It with the Sirris R46 2SC Shock
Complete your Ultra Bee suspension setup with the Sirris R46 2SC MX Tune shock. Designed to work alongside the F43, it adds independent high-speed and low-speed compression adjustment with complementary MX Tune damping for balanced handling, traction, and control.
Specs
Specification
Details
Architecture
Upside-down fork with symmetrical and adjustable pressurized closed-cartridge dampers
Travel
260mm
Free Length
856mm
Fork Weight, Including Clamps and Steerer
22 lbs / 10 kg
Stanchions
Ø43mm, high-tensile steel with hard chrome
Outer Tubes
Seamless 7050 aluminum, Type 3 hard anodized coating
Dropouts
Forged 6061 aluminum, Type 3 hard anodized coating
Brake Mounting
Sized for stock Ultra Bee calipers and 240mm rotors
Triple Clamps
Forged 6061 aluminum, Type 3 hard anodized coating
Steer Tube
Seamless 7050 aluminum, Type 2 anodized coating
Damping
MX Tune; symmetrical, adjustable closed cartridges with spring-backed IFP, high-flow pistons, fully tunable compression and rebound valving, and separate damping and lubrication oil circuits
Bottom-Out Control
Progressive hydraulic bump stop
Damper Bodies
Seamless 7050 aluminum, Type 3 hard anodized coating
Springs
Dual-side high-tensile steel springs with adjustable preload
Adjusters
External tool-free low-speed compression adjustment and tool-operated rebound adjustment
Seals
NOK Heavy Duty seals
Bushings
Premium Daido bushings with custom Sirris proprietary design
"I got tracking for the warp9 rear wheel already. I’m so thankful! Can’t say thank you enough for all your help and for answering my questions so thoroughly.
The entire experience of doing business with you has been incredible. I honestly don’t remember the last time I received such great support from any company in any industry. I will most definitely be ordering from you in the future. Thank you so much!
-Caleb M.
"Your YouTube channel was essential for me learning about the Ultra Bee...The in-depth spec coverage, riding tests, range tests and upgrade reviews are great. Really good editing of the videos, too. Watching Tucker's riding, the footage is great and when you see a guy shred on these bikes, it gives you a really good feel for what these things are capable of... and makes me trust your guys' opinions. Keep up the good work!"
