TUNING, SPRING RATES, SAG AND ADJUSTMENTS

Dial in your ride specific to your riding preference and rider weight. Learn about our different tunes, spring rates, sag setup and how to adjust your suspension.

FORK AND SHOCK TUNING OVERVIEW

Sirris offers a wide variety of tuning options to fit your riding needs. The internal tuning is accomplished by mixing the perfect match of spring weight, compression settings, rebound settings, preload settings and oil weight. All are internally adjustable and serviceable by a trained technician or service center.

Hard Enduro Tune* 

Hard Enduro tune is a race-only tune that maximizes plushness and extreme terrain capability at the expense of other riding types. At slower speeds, it’s designed to soak up the impact of the roughest chop and boulders. This tune has a highly progressive damping character with super soft low-mid speed damping paired with a high speed damping catch. 

Trail Tune

Our most versatile and aggressive tune. It’s sporty and supportive, designed for going fast over a wide variety of terrain. Firmer than our Hard Enduro tune, but still substantially capable on the nastiest terrain. It’s also not a Moto tune, but delivers good bottoming resistance on g-outs and small jumps.

EBMX Tune

EBMX tune is specifically made for modified bikes in collaboration with EBMX.  It’s designed to work with a longer travel front fork (260mm) and is intended for a mix of light moto and aggressive trail. It uses a firmer fork tune than Trail tune for bottoming resistance and a stiffer rear spring to handle increased bike weight and power delivery of EBMX components.

MX Tune

MX Tune is a motocross specific tune with balance, control, and bottoming resistance for the fastest speeds. Firm suspension for maximum control and support for huge jumps, whoops and fast cornering. If you select the EBMX or MX spec, you’ll compromise a bit of trail plushness for improved bottoming resistance.

SX Tune*

SX Tune is a super aggressive firm tune to handle the biggest landings. Ultra firm to absorb the biggest hits.

*NOTE: Hard enduro and SX Tunes are currently not available for sale from the factory. A Sirris service center will have the appropriate parts to retrofit these specialized race tunes.

TUNING DETAILS & RIDER WEIGHT RANGE

Every rider, every riding style. Sirris offers multiple weight ranges to choose from when selecting your suspension.
Listed weight ranges are body weight without riding gear.

SETTINGS NOTE: 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.

*OIL NOTE: Sirris uses Shell Tellus S2 VX15 (5wt) in the fork cartridge and Shell Tellus S2 VX68 (20wt) as the bath oil. These are cross compatible with other high quality 5wt and 20wt suspension fluids.  Sirris uses a semi-synthetic 2.5wt oil in the shock that is also compatible with other high quality 2.5wt aftermarket suspension fluids. You can use 5wt/20wt oils of your preference, Lubefinder.com can be used to source the fork oils. KYB K2C can be used in the shock and has wide availability.

SPRING RATES

It is not unusual for riders to require spring rates different than what we offer on our light/medium/heavy 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 a 10 N/mm rate bump 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: 4.0, 4.4, 4.8, 5.0, 5.4, and 5.8.  Refer to chart above for spring weights included.

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 standard Surron Trail Med Rate is 4.6 N/mm. It has a 4.4 one side, and 4.8 on the other side to get the average of 4.6 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.

SHOCK SPRING RATES 

R46 spring rates (in N/mm) available are: 75, 85, 90, 95, 105, and 115. Refer to chart above for spring weights included.   

If you upgrade your bike with a larger battery, we recommend going up 10 N/mm spring rate to accommodate the heavier bike weight.

Surron Ultra Bee shock springs require a spring compressor because of the short shock length. Max preload = 20mm 

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 on previous page.

SAG SET-UP 

  1. Start with recommended rebound, compression, and preload settings.
  2. 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%.
  3. 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.)
  4. 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 2mm implies there’s an incorrect spring rate. 5mm and 10mm positions are marked on the gold outer tube.
  5. 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.
  6. When you increase rebound, remove 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.
  7. 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.

COMPRESSION ADJUSTMENTS

LOW-SPEED COMPRESSION ADJUSTMENT 

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

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.

Refer to chart above to find your compression settings. 

REBOUND ADJUSTMENTS

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.

Refer to chart above to find your rebound settings. 

FORK AIR BLEED

Your fork will not build significant pressure, meaning you will not need to regularly open bleed screws. Bleed screws should be vented when there is a significant change in elevation. Turn the Phillips screw counter clockwise to let air out. 

WARNING AND SAFETY INFO

Sirris products should be installed by a professional suspension technician and must follow Sirris installation procedures. Improperly installed suspension can fail causing rider to lose control resulting in SEVERE INJURY OR DEATH. 

Worn or damaged suspension components can negatively impact performance and safety of the motorcycle. If suspension components appear worn or damaged, contact an authorized service center for assistance.  

Do not alter or modify any part of Sirris products in any way. It may cause product failure resulting in SEVERE INJURY OR DEATH. 

Misuse of Sirris suspension may cause failure, resulting in damage or SEVERE INJURY OR DEATH. 

DO NOT carry more than one person on a vehicle installed with Sirris suspension. 

Improper service or use of non-Sirris parts with Sirris suspension may cause the fork or shock to malfunction, resulting in SEVERE INJURY OR DEATH. 

If your fork loses oil, makes abnormal noises, tops or bottoms out easily, do not ride the Sirris suspension. Contact Sirris or an authorized Sirris service center for repair, service or inspection. 

Sirris suspension may fail under rare circumstances that cause bending and/or breaking to any part of the fork or shock. Anything that causes loss of nitrogen, oil (such as a collision or extended periods of non-use) may also cause your fork or shock to fail. A damaged or leaking product could fail, resulting in a crash and SEVERE INJURY OR DEATH. If you think your product has been damaged or not working properly, do not ride and immediately contact Sirris or authorized Sirris service center for inspection or repair.