INNTECK KYB Fork Springs for YAMAHA, FANTIC, BETA, RIEJU, SUZUKI and KAWASAKI 2014-2027

The INNTECK KYB pair of fork springs is designed for BETA RR 125, RR 250, RR 300, RR 350, RR 390, RR 430, RR 480, RX 250, RX 300, RX 350, RX 450, FANTIC XE 125, XE 300, XEF 250, XEF 310, XEF 450, XX 125, XX 250, XXF 250, XXF 450, YAMAHA WRF 250, WRF 450, YZ 125, YZ 250, YZF 250, YZF 450, SUZUKI RMZ 250, RMZ 450, RIEJU MR 250, MR 300 and KAWASAKI KXF 250 from 2014 to 2027. The spring rate sets the height at which the fork works in its travel. With springs matched to your weight, the front end holds its attitude under braking and on landings, and the damping adjustments get back into their effective range.

Specifications

• Brand: INNTECK
• Manufacturer part numbers: QS3138, QS3140, QS3142, QS3144, QS3146, QS3148, QS3150, QS3152, QS3154, QS3156
• Diameter: 43.5 mm, length: 498 mm
• Sold as a pair (one spring per fork leg)
• Available versions: 3.8 N/mm: ref. QS3138; 4 N/mm: ref. QS3140; 4.2 N/mm: ref. QS3142; 4.4 N/mm: ref. QS3144; 4.6 N/mm: ref. QS3146; 4.8 N/mm: ref. QS3148; 5 N/mm: ref. QS3150; 5.2 N/mm: ref. QS3152; 5.4 N/mm: ref. QS3154; 5.6 N/mm: ref. QS3156

Choosing the right spring rate

Start from the original spring rate (see the bike's manual) and adjust for your riding weight with gear: heavier than the standard rider, go up one step; lighter, go down one step. In enduro, people often choose something a little softer than in motocross for extra comfort.

When to replace it?

• The fork bottoms out often or dives hard under braking: springs too soft for you.
• The front end sits high, bounces and the bike understeers: springs too stiff.
• You weigh clearly more or less than the standard rider the manufacturer designed for.
• Springs sagged after many hours: the fork sits lower in its travel than it did originally.

Spring rate is given in N/mm. Manufacturers also quote it in kg/mm: 1 kg/mm is about 9.81 N/mm (0.46 kg/mm ≈ 4.5 N/mm). Check the type and diameter of your fork: the spring must have the right length and diameter.

Fitting tips

1. Note your settings and the height of the tubes in the clamps, then remove the fork.
2. Open each leg following the manual for your fork and replace the spring, reusing the original washers and spacers.
3. Reset the fork oil level to the height given in the manual: it affects the end of the stroke.
4. Refit the fork and tighten the clamps to the specified torque, then check the front rider sag.

Spare parts and items to plan

• Fork oil : LIQUI MOLY 10W 500 ml
• Fork oil seals : ATHENA P40FORK455139 · ATHENA P40FORK455076

Frequently asked questions

Do I have to change both springs?
Yes, always as a pair, with the same spring rate on both sides, except on forks with a single spring.

Are springs enough to transform the fork?
They put the fork back at the right height for your weight. The damping is then adjusted with the compression and rebound clickers.

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
BETA RR 125 2024
BETA RR 125 2023
BETA RR 250 2024
BETA RR 250 2023
BETA RR 300 2024
BETA RR 300 2023
BETA RR 350 2024
BETA RR 350 2023
BETA RR 390 2024
BETA RR 390 2023
BETA RR 430 2024
BETA RR 430 2023
BETA RR 480 2024
BETA RR 480 2023
BETA RX 250 2027
BETA RX 250 2026
BETA RX 300 2025
BETA RX 300 2024
BETA RX 300 2023
BETA RX 300 2022
BETA RX 350 2027
BETA RX 350 2026
BETA RX 450 2027
BETA RX 450 2026
BETA RX 450 2025
BETA RX 450 2024
BETA RX 450 2023
FANTIC XE 125 2027
FANTIC XE 125 2026
FANTIC XE 125 2025
FANTIC XE 125 2024
FANTIC XE 125 2023
FANTIC XE 125 2022
FANTIC XE 300 2027
FANTIC XE 300 2026
FANTIC XE 300 2025
FANTIC XE 300 2024
FANTIC XEF 250 2027
FANTIC XEF 250 2026
FANTIC XEF 250 2025
FANTIC XEF 250 2024
FANTIC XEF 250 2023
FANTIC XEF 250 2022
FANTIC XEF 250 2021
FANTIC XEF 310 2027
FANTIC XEF 310 2026
FANTIC XEF 310 2025
FANTIC XEF 310 2024
FANTIC XEF 450 2027
FANTIC XEF 450 2026
FANTIC XEF 450 2025
FANTIC XEF 450 2024
FANTIC XEF 450 2023
FANTIC XX 125 2027
FANTIC XX 125 2026
FANTIC XX 125 2025
FANTIC XX 125 2024
FANTIC XX 125 2023
FANTIC XX 125 2022
FANTIC XX 250 2027
FANTIC XX 250 2026
FANTIC XX 250 2025
FANTIC XX 250 2024
FANTIC XX 250 2023
FANTIC XX 250 2022
FANTIC XXF 250 2027
FANTIC XXF 250 2026
FANTIC XXF 250 2025
FANTIC XXF 250 2024
FANTIC XXF 250 2023
FANTIC XXF 250 2022
FANTIC XXF 450 2027
FANTIC XXF 450 2026
FANTIC XXF 450 2025
FANTIC XXF 450 2024
FANTIC XXF 450 2023
FANTIC XXF 450 2022
KAWASAKI KXF 250 2024
KAWASAKI KXF 250 2023
KAWASAKI KXF 250 2022
KAWASAKI KXF 250 2021
KAWASAKI KXF 250 2020
RIEJU MR 250 2027
RIEJU MR 250 2026
RIEJU MR 250 2025
RIEJU MR 250 2024
RIEJU MR 250 2023
RIEJU MR 250 2022
RIEJU MR 300 2027
RIEJU MR 300 2026
RIEJU MR 300 2025
RIEJU MR 300 2024
RIEJU MR 300 2023
RIEJU MR 300 2022
SUZUKI RMZ 250 2027
SUZUKI RMZ 250 2026
SUZUKI RMZ 250 2025
SUZUKI RMZ 250 2024
SUZUKI RMZ 250 2023
SUZUKI RMZ 250 2022
SUZUKI RMZ 250 2021
SUZUKI RMZ 250 2020
SUZUKI RMZ 250 2019
SUZUKI RMZ 450 2027
YAMAHA WRF 250 2027
YAMAHA WRF 250 2026
YAMAHA WRF 250 2025
YAMAHA WRF 250 2024
YAMAHA WRF 250 2023
YAMAHA WRF 250 2022
YAMAHA WRF 250 2021
YAMAHA WRF 250 2020
YAMAHA WRF 450 2027
YAMAHA WRF 450 2026
YAMAHA WRF 450 2025
YAMAHA WRF 450 2024
YAMAHA WRF 450 2023
YAMAHA WRF 450 2022
YAMAHA WRF 450 2021
YAMAHA WRF 450 2020
YAMAHA WRF 450 2019
YAMAHA YZ 125 2027
YAMAHA YZ 125 2026
YAMAHA YZ 125 2025
YAMAHA YZ 125 2024
YAMAHA YZ 125 2023
YAMAHA YZ 125 2022
YAMAHA YZ 250 2027
YAMAHA YZ 250 2026
YAMAHA YZ 250 2025
YAMAHA YZ 250 2024
YAMAHA YZ 250 2023
YAMAHA YZ 250 2022
YAMAHA YZF 250 2027
YAMAHA YZF 250 2026
YAMAHA YZF 250 2025
YAMAHA YZF 250 2024
YAMAHA YZF 250 2023
YAMAHA YZF 250 2022
YAMAHA YZF 250 2021
YAMAHA YZF 250 2020
YAMAHA YZF 250 2019
YAMAHA YZF 250 2018
YAMAHA YZF 250 2017
YAMAHA YZF 250 2016
YAMAHA YZF 250 2015
YAMAHA YZF 250 2014
YAMAHA YZF 450 2027
YAMAHA YZF 450 2026
YAMAHA YZF 450 2025
YAMAHA YZF 450 2024
YAMAHA YZF 450 2023
YAMAHA YZF 450 2022
YAMAHA YZF 450 2021
YAMAHA YZF 450 2020
YAMAHA YZF 450 2019
YAMAHA YZF 450 2018
YAMAHA YZF 450 2017
YAMAHA YZF 450 2016
YAMAHA YZF 450 2015
YAMAHA YZF 450 2014