Sirris F43 CMX Front Suspension Specs, Installation guide, and Fitment

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Sirris F43 CMX Front Suspension

Upgrade your electric moto with a Sirris F43 CMX fork! This race ready, and built to last platform is ready to move from E-Moto to E-Moto as you change to the next best bike on the market. It is designed and built in America with quality components that will surely outlast the bike you put it onto!

CMX TUNING DETAILS / RIDER WEIGHT RANGE / SET UP GUIDE

CMX forks are tuned for versatile performance across road, trail, and track. Riders may prefer softer or firmer settings depending on their style. The Sirris fork is fully rebuildable, and recommended service centers can assist with custom tuning as needed.

If you don’t fit into MED or above HVY weight classes, we sell lighter and heavier after market springs (3.2 N/mm to 6.2 N/mm).

Spring rate changes are easy enough for most home mechanics to complete the job.

• Listed weight ranges are body weight without riding gear (15 pounds of riding gear is calculated into the weight ranges)

• Weights of upgrades (battery, controller, etc) need to be added to rider weight

CMX TUNING DETAILS / RIDER WEIGHT RANGE (continued)

STARTING POINT NOTES:

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

SPRING RATES

It is not unusual for riders to require spring rates different than what we offer on our tunes. If you’re at the heavy end of one. of our categories, you may choose to go up a rate based on your riding style. The inverse is true if you’re at the bottom of one of our categories. Heavily modified bikes typically need to go up a weight class in the rear. Riders who ride with their weight back or who ride seated may need more rear rate and may need to drop the forks to properly weight the front. An unweighted front is the most common cause of fork harshness.

Sirris offers a full selection of rates for your tuning needs. When rates vary greatly from stock, valving changes may be required to optimize performance.

FORK SPRING RATES

F43 spring rates (in N/mm) available are: 3.2, 3.6, 4.0, 4.4, 4.8, 5.0, 5.4, and 5.8.

Fork springs for Sirris F43 forks are sold as individual units. Two springs are required for your fork. You can combine two sequential rates to get an “in between” total fork spring weight if desired.

For example, our Surron Light Bee X (LBX) Medium Rate is 3.4 N/mm. It has a 3.2 one side, and 3.6 on the other side to get the average of 3.4 for the fork.

Stiffer rate spring should always be placed in brake side leg.

Oil and clicker settings should be the same on both sides, you do not need to individually change any settings on your left or right fork leg if you use two different spring rates.

Full Tuning Guide:

Tuning:

At Sirris, tuning is done with stock wheel and tire sizes. If you raise the front or lower the rear, you’ll need to rebalance the motorcycle. When fine tuning your bike, always focus on front/rear balance first. If your spring rates and/or balance is incorrect, you will never successfully compensate with damping clickers.

If the bike turns poorly or pushes wide, the front is likely too high or too light:

Add rear spring rate and/or shock preload. Or reduce front spring rate.
Alternatively, push forks higher in clamps, lowering the front of the motorcycle. Remember that 3mm is a large change.

If the front wheel tucks, or the handling character is nervous, the front is likely too low or too heavy:

Reduce rear spring rate and/or shock preload. Or add front spring rate.
Alternatively, push the forks down in the clamps, raising the front of the motorcycle. Remember that 3mm is a large change.

If the fork feels harsh, and it’s properly broken in, you could have one of the following issues:

Fork spring rate too high for your weight
Clicker settings improperly adjusted
Too much rear sag

ADJUSTMENTS

SAG RANGE AND BALANCE (Sag is measured with rider in riding gear, standing on pegs in riding position.)

Before changing clicker positions, always make sure the balance of your bike is correct. Too much weight on front or rear will be felt as harshness, instability, or inconsistent grip. Sag is the amount your suspension compresses under your weight and riding gear. Rear sag should be between 25% and 30%. If your rear rider sag is greater than 30%, your fork will not work as intended. An unweighted front is the most common cause of fork harshness. Front sag should be between 12% and 18%. Adjust as needed with preload, spring rate, and fork clamp height. Turn your compression adjusters to the closed position (full clockwise) until they stop. Then back them out (counterclockwise) according to the number of clicks indicated in the charts.

SET-UP

Start with recommended rebound, compression, and preload settings.
Adjust rear shock to recommended sag by changing spring preload*. If preload is greater than 8mm, go up a rate. If less than 2mm, go down a rate. If you ride with your weight more back, run sag closer to 25%. If you ride with your weight more forward, run sag closer to 30%.
The best way to adjust fork sag is by changing spring rate. Stock preload is 5mm. You can safely use 0mm but may experience some spring rattle at full extension. You can safely use 10mm or 15mm but you may need to add more rebound damping than optimal. (this is closed cartridge damper, pre-load is adjusted via circlip groove on outside of the cartridge. Grooves are in 5 mm increments.)
Adjust fork position in clamps to achieve the correct balance on bike. If the fork rides high in the travel and feels harsh, move forks up in clamps (move front of bike closer to ground). If greater than 10mm of the outer tube is showing above top clamp, your front or rear spring rate is likely incorrect. Conversely, less than 0mm implies there’s an incorrect spring rate. 5mm and 10mm positions are marked on the gold outer tube.
Adjust clickers by changing 2 clicks at a time. If your suspension is properly balanced and sprung, changing 2 clicks will be felt as a noticeable good or bad change.
When you close the rebound adjuster, it will increase both compression and rebound forces. To only increase rebound forces, open the corresponding number of compression clicks to keep overall force capacity. For example, 2 clicks less rebound should be paired with 2 clicks more compression.
If you find yourself within 5 clicks of full open or closed, something is wrong. Most likely problems are shock settings, shock spring, fork spring, or fork position.

ADJUSTMENTS

LOW-SPEED COMPRESSION ADJUSTMENT

Twist the dial on fork top cap counter-clockwise for lighter compression (open) or clockwise for firm (closed) compression.

Adjust left and right legs evenly.

If you find yourself within 5 clicks of full open or closed, something is wrong. It could be incorrect spring rate, fork height, or shock tune.

REBOUND

Rebound control the rate of speed at which the suspension extends after compressing. The rebound adjustment is dependent on the spring rate. For example, stiffer springs require slower rebound settings.

Use a flat screw driver to turn the center compression adjust screw counter-clockwise for faster rebound (open) or clockwise for slower (closed) rebound.

If you find yourself within 5 clicks of full open or closed, something is wrong. It could be either your spring rate, fork height, or the tune could be incorrect for your riding style.

Full Installation Guide:

Video Guide:

This guide provides a step-by-step process for installing your new fork.

Important Safety Information

Improper installation can lead to serious injury or death.
Do not modify any Sirris parts.
Always inspect for wear or damage.

Break-In Period

The Sirris F43 fork has a symmetrical closed cartridge design.
Allow 5 hours of riding to break it in before making significant adjustments to clicker positions or valving.

Service Intervals

Regular maintenance is crucial for optimal performance.
Service intervals vary depending on riding conditions and frequency.

Oil Replacement:

Oil Type	General Use	Racing
Fork Bath Oil	30 hrs	10 hrs
Fork Cartridge Oil	60 hrs	20 hrs
Shock Oil	60 hrs	20 hrs

Bushing and Seal Service:

Oil Type	General Use	Racing
Fork Seals and Bushings	90 hrs	30 hrs
Shock seals and Bushings	90 hrs	60 hrs

Installation Guide

Tools Required

Torque wrench (3-70 Nm)
Grease
Medium strength Loctite
Allen keys
Sockets
Step-by-Step Installation

Remove Stock Fork:
- Remove stock fork while maintaining stock upper bearing, split race, and seal on the frame.
Unbox and Disassemble Sirris F43 CMX Fork

Install Brake Bracket:
- Use M6 bolts at 18 Nm torque.
- Note: Upgrade to a 220mm rotor if needed.

Grease Lower Bearing:
- Grease the lower bearing with suitable bearing grease.
- Preferred Grease: Maxima Waterproof Grease

Install Lower Clamp:
- Install lower clamp onto the frame with correct seals and spacers.

Install Upper Clamp:
- Install upper clamp onto the frame.
- Place spacers above the upper clamp

Install Direct Mount Stem & Handlebars:
- Note: A stem that clamps on the steerer tube will NOT work.

Install Fork Legs:
- Torque lower clamp bolts to 10 Nm with grease.
- Remember to include the fork bumper.

Tighten Top Cap
- Tighten the top cap to the desired bearing tension

Torque all Triple Clamp Bolts:
- Torque to 10 Nm with grease.

Install Brake Caliper:
- Wait to torque caliper bolts until after front wheel installation.

Install Brake Line on Fork Guard:

Install Front Fender:

Attach Brake Line Guide:
- Use supplied zip tie.

Install Number Plate (if applicable):

Install Front Wheel:
- Use supplied axle and model-specific spacers.

Install Axle Bolt:
- Torque to 30 Nm with grease.

Torque Pinch Bolts:
- Torque brake side drop out pinch bolts to 10 Nm with grease.
- Ensure axle is floating, then torque non-brake side pinch bolts to 10 Nm with grease.

Check Settings:
- Check compression and rebound clicker settings as recommended.

Torque Specs

Component:	Torque Spec (N.m.)
Upper Triple Clamp Pinch Bolts	10 N.m.
Lower Triple Clamp Pinch Bolts	10 N.m.
Fork Guard Bolts	5 N.m.
Axle Dropout Bolts	10 N.m.
Brake Caliper Adapter	18 N.m.
Axle Bolt	30 N.m.
Bearing Tension Bolt	Rider Preference

Brake Line Routing

LIMITED WARRANTY INFO

Your Sirris fork and shock are warrantied against manufacturing defects for a period of 2 years. Normal wear and regular maintenance are not covered.

Sirris makes the following LIMITED WARRANTY with respect to its suspension products:

LIMITED TWO (2) YEAR WARRANTY ON SUSPENSION PRODUCTS

Subject to the limitations, terms and conditions hereof, Sirris warrants, to the original retail owner (consumer) of each new Sirris suspension product, that the Sirris suspension product, when new, is free from defects in materials and workmanship. This limited warranty expires two (2) years from the date of the original Sirris suspension product retail purchase from an authorized Sirris dealer or from a Sirris authorized Original Equipment Manufacturer where Sirris suspension is included as original equipment on a purchased vehicle.

TERMS OF WARRANTY

This limited warranty is conditioned on the Sirris suspension product being operated under normal conditions and properly maintained as specified by Sirris. This limited warranty is only applicable to Sirris suspension purchased new from an authorized Sirris source and is made only to the original retail owner (consumer) of the new Sirris suspension product and is not transferable to subsequent owners. Should it be determined, by Sirris in its sole and final discretion, that a Sirris suspension product is covered by this limited warranty, it will be repaired or replaced, by a comparable model, at Sirris’s sole option, which will be conclusive and binding. THIS IS THE EXCLUSIVE REMEDY UNDER THIS LIMITED WARRANTY. ANY AND ALL OTHER REMEDIES AND DAMAGES THAT MAY OTHERWISE BE APPLICABLE UNDER THIS LIMITED WARRANTY ARE EXCLUDED, INCLUDING, BUT NOT LIMITED TO, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR PUNITIVE DAMAGES.

This limited warranty does not apply to normal wear and tear, malfunctions or failures that result from abuse, neglect, improper assembly, alteration or modification, improper or unauthorized repair or maintenance, crash, accident or collision, or other abnormal, excessive or improper use.

THIS IS THE ONLY WARRANTY MADE BY SIRRIS ON ITS SUSPENSION PRODUCTS AND COMPONENTS, AND THERE ARE NO WARRANTIES WHICH EXTEND BEYOND THE DESCRIPTION HEREIN. ANY WARRANTIES THAT MAY OTHERWISE BE IMPLIED BY LAW INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXCLUDED.

When making a claim under this Limited Warranty you will be required to provide to an authorized Sirris Service Center:

1. The Product (or the affected part) and

2. A copy of the original proof of purchase, which clearly indicates the name and address of the seller, the date and place of purchase, the product part number and if utilized, a serial number. If Sirris products are sold as part of a complete motorcycle, the motorcycle brand, model, model year, and serial number should be included.

Tags: Suspension