The facts.
| Brand | STM |
|---|---|
| Part Number | FYA-S120 |
| Type | Slipper clutch (anti-hopping clutch) |
| Fitment | Yamaha YZF-R1 (2007–2008) |
| Slipper Mechanism | Patented ball-ramp system |
| Spring Type | Diaphragm spring |
| Weight Saving | Approx. 0.7–0.8 kg (reduced rotating mass) |
DescriptionThe whole story▼
Whether you're threading through weekend mountain roads or pushing hard on track days, the STM slipper clutch for the Yamaha YZF-R1 (2007-2008) delivers a level of rear-wheel composure and clutch feel that the standard unit simply cannot match. Part number FYA-S120, it is a direct, practical upgrade that pays dividends every time you brake hard into a corner.
Key Features
- Prevents engine over-rev on aggressive downshifts, keeping the rear wheel settled and the chassis stable under hard braking
- Reduces rear-wheel hop and chatter, improving traction and confidence through the corner entry phase
- Lowers the trigger impulse for highsider incidents, adding a meaningful safety margin during fast, committed riding
- Allows controlled rear-wheel slide for a more fluid, adjustable cornering style
- Improved clutch engagement feel in corners — the diaphragm spring eliminates pressure-plate judder for a smoother, more progressive release
- Weight saving of approximately 0.7–0.8 kg through reduced rotating mass, sharpening throttle response and overall performance on the YZF-R1
- Patented ball-ramp mechanism governs the slipper function with precision at high engine speeds
Engineering and Build Quality
STM is one of the most respected names in aftermarket clutch technology, with decades of racing pedigree feeding directly into their road and track product range. The FYA-S120 is engineered to OEM fitment standards, meaning installation is straightforward and no additional modifications to the clutch basket or actuation system are required. The patented ball-ramp design is the heart of the system: under deceleration, the ramps allow the clutch to partially disengage proportionally to the degree of engine braking, preventing the rear tyre from locking or hopping without removing drive entirely. When you open the throttle again, the ramps re-engage the clutch smoothly and instantly.
The diaphragm spring replaces the conventional coil-spring stack, eliminating the plate flutter that causes the harsh, inconsistent feel many riders notice in the standard clutch at high rpm. The result is a lever pull that is lighter, more progressive, and far easier to modulate — a benefit that is just as noticeable on a spirited road ride as it is on circuit.
Everyday Usability and Real-World Value
It is easy to assume a slipper clutch is only relevant if you are chasing lap times. In practice, the FYA-S120 earns its keep every ride. Stop-start traffic, aggressive overtakes with rapid gear changes, and unfamiliar roads where braking points are uncertain — all of these scenarios become less stressful when the rear wheel is no longer a variable you need to manage consciously. The weight reduction also has a perceptible effect on the engine's willingness to rev, making the YZF-R1 feel lighter and more responsive without any other modification.
Fitment and Compatibility
This clutch is a precise fit for the following model:
- Yamaha YZF-R1 — model years 2007 and 2008
Always confirm your frame and engine number against the fitment data before ordering if your machine has been modified or has a non-standard engine specification.
Specifications
| Brand | STM |
|---|---|
| Part Number | FYA-S120 |
| Type | Slipper clutch (anti-hopping clutch) |
| Fitment | Yamaha YZF-R1 (2007–2008) |
| Slipper Mechanism | Patented ball-ramp system |
| Spring Type | Diaphragm spring |
| Weight Saving | Approx. 0.7–0.8 kg (reduced rotating mass) |
| Category | Engine and clutch |
FitmentWhich bikes this fits▼
- Yamaha YZF-R1 (2007–2008)
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