Sirris F43 Fork CMX Tune: Sur-Ron Light Bee X

Take your Sur-Ron LBX to the next level with the Sirris F43 CMX Fork. This 220mm travel fork is engineered without compromise specifically for the Sur-Ron Light Bee X for high-performance, aggressive riding. The CMX Tune (Compact Motocross) paired with the race-proven F43 platform brings elite-level suspension tech to the electric dirt bike world.

Sirris F43 CMX Fork Features

• 220mm Travel — (17mm more than stock) adds cushioning for aggressive riding
• Tool-Free Compression Adjusters — for quicker changes during mid ride without any tools needed
• 178mm Fork Spacing — allows unlimited tire selection from aggressive knobby to supermoto treads
• Drop Clamp Option for 21" Wheels — allows for fitment of 21” wheel by raising the front end an additional 25mm while retaining 220mm travel (raising the front end maintains balance of the bike if paired with a longer shock that raises the rear)
• Scalloped Clamps — for aggressive, trick styling
• Direct Mount Stem (DM Ready) — lightweight billet clamps with DM stem designed for hassle-free setup (no extra parts needed)
• Axle & Brake Mounts — ultra-stiff and configurable
  • Axle and drop out assembly promotes front-end feel and steering precision
  • Universal lugs, custom axle spacers and new brake mounts allow for easier stocking, and allows rider greater wheel and brake options
  • Replaceable caliper mount brackets allow for caliper upgrades
• Symmetrical Closed Cartridge Dampers — specifically tuned for each model, and fully tunable for spring rate and damping for balanced performance
• Motorcycle-Style Top Cap — increases ability to tension steering bearings and retain torque
• Available in MEDIUM and HEAVY tun

OEM Sur-Ron Light Bee X Compatibility The triple clamps and guards perfectly align with the Sur-Ron LBX fairing and cable routing. Additionally, the CMX F43 Fork upgrade is compatible with the Light Bee stock display, fender, and brake as well. Shock Suspension Pairing For optimal bike performance, we recommend using an EXT Arma Shock, Ohlins TTX22M with EXT Spring, or equivalent.

MEDIUM TUNE FORK - Use with: 79 N/mm (450lb) stock spring, compression 5, rebound 7, 3mm preload.

HEAVY TUNE FORK - Use with: 88 N/mm (500lb) spring, compression 3, rebound 5, 3mm preload.

F43 CMX Fork Specs

Architecture	Upside down fork
Travel	220mm
Free length	775mm (drop clamp option adds another 25mm of extended length)
Fork Spacing	178mm - allows for unlimited tire choice (dirt or street)
Fork weight	4 kg per leg (driven by sturdy construction required for the forces and speeds encountered when pushing these bikes to their limits without compromising performance)
Stanchions	43mm - high tensile steel with hard chrome
Outer tubes	Seamless 7050 aluminum, type 3 hard anodized coating
Drop outs	6061 aluminum, type 2 anodized coating Replaceable caliper mount brackets allow for caliper and wheel upgrades
Axle	Ultra-high tensile hard chromed axle increases steering precision and confidence
Triple clamps	Billet 6061 aluminum, type 2 anodized coating, 3 color options (blue, red, black) Optional drop clamp allows for 21” front wheel conversion (black only)
Steer tube	Seamless 7050 aluminum, type 2 anodized coating
Damping	Symmetrical, adjustable closed cartridge with spring backed modified IFP
Damper bodies	Seamless 7050 aluminum, type 3 hard anodized coating
Rebound	Dual side high tensile steel spring, adjustable
Adjusters	External tool-free compression, rebound adjustment (rebound adjusted using tool)
Seals	NOK MX seals
Bushings	Daido MX bushings
Guards	High impact PP, 210° wraparound

CMX Tuning Details & Rider Weight Ranges

Sirris offers 2 weight ranges to choose from when selecting your CMX Tune F43 Fork for Sur-Ron LBX. Listed weight ranges are body weight with 15 lbs of riding gear. Weights of upgrades (e.g. battery, controller, motor) need to be added to rider weight.

	Medium	Heavy
Rider Weight (lbs) (No Gear)	140-180	180-220
Spring Rate (N/mm)	3.6/3.2	3.6/3.6
Fork Height in Upper Clamp (mm)	5	5
Compression Setting	22	20
Rebound Setting	22	20
Preload Setting (mm of preload R and L fork legs)	5/5	5/5
Oil Volume (Bath Oil)	100cc	110cc
Oil Weight* (bath/cartridge)	20/5	20/5
Headset Spacer 1mm thick washer beneath seal, PN 430-38-017	None
Steerer Spacer 1mm thick above top clamp / beneath top cap	430-38-018 x2
Caliper Bracket	430-22-032, 74mm
Wheel Spacers	430-28-016 x2

SETTINGS: Settings are number of clicks from the closed position (full clockwise). Once they are in the closed position, back them out (counter-clockwise) according to the number of clicks indicated in the chart above to get you to factory settings. CMX Tune Starting Point:

• Assuming neutral riding position, and 15 lbs gear
• Weights of upgrades (battery, controller, etc) to be added to rider weight
• Riders close to a weight cut off need to adjust preload to compensate
• Very aggressive/pro riders to consider +1 weight class and drop preload to get sag. Especially if in the upper range.
• Rider preference and riding conditions may require a different setup

Example:

• 160 lb rider without riding gear, 20 additional lbs with upgraded controller/battery
• Weight calculation 160+20=180
• Aggressive rider = Heavy tune with low preload
• Relaxed rider = Medium tune with high preload

Sirris F43 Fork Installation

Easy Direct Mount Setup Upgrade your stock Sur-Ron Light Bee X easily with the direct mount front suspension system. No additional modifications or parts are required. 5-Hour Break-In Period Recommendation The Sirris F43 Fork will break-in during the first 5 hours of use with significant improvements in friction. We recommend that you don’t make significant changes to clicker positions or valving until after the 5-hour break-in period. Sirris F43 CMX Fork Owner’s Guide (PDF) ›