YXZ OEM Clutch Upgrade Kit (Includes):
- LESS SLIPPAGE!
- 30% Stronger Pressure Plate Spring
- 3 OEM Friction Plates (replaces 3 OEM damper springs)
- New OEM Yamaha Clutch Cover Gasket
There is NO negative impact on shifting. The Clutch Pedal fells only slightly stiffer but you really had to try and take notice (jumping back and forth between a Stock Vehicle and a modified Clutch Vehicle).
MPI Clutch Testing at 155HP without Modification
- We observed up to 9% slippage, but for never more than 500mSec (1/2 of a second). After 500mSec, the ratio would become flat (actual value dependent on gear 1-5). Boost was run at 155HP target. Upon a 500 mile inspection of the clutch discs we saw nothing that looked HOT (which is typically evident of a slipping clutch). Measurement of the 8 larger friction plates ranged from 0.119 to 0.121in and the smaller 3 being slightly thicker 0.121 to 0.122in. The plates were all 0.080in. The newer unit may have been 0.001in larger, but one of the new large friction plates was actually 0.118in (.001 smaller than the smallest one from the durability unit).
MPI Clutch Testing at 200HP
- STOCK CLUTCH: We observed up to 12% slippage, but for never more than 750mSec (3/4 of a second). After 750mSec, the ratio would become flat (actual value dependent on gear 1-5). Boost was run at 200HP target. Upon a 100 mile inspection of the clutch discs we saw slight bluing but still nothing that looked terribly HOT (which is typically evident of a slipping clutch). Measurement of the 8 larger friction plates ranged from 0.117 to 0.120in and the smaller 3 being slightly thicker 0.118 to 0.122in. The plates were all 0.078 to 0.080in.
- MPI CLUTCH KIT: We observed up to 8% slippage, but for never more than 500mSec (1/2 of a second). After 500mSec, the ratio would become flat (actual value dependent on gear 1-5). Boost was run at 200HP target. Upon a 150 mile inspection of the clutch discs we saw NO bluing and nothing that looked HOT (which is typically evident of a slipping clutch). Measurement of the 11 large friction plates ranged from 0.119 to 0.121in. The plates were all 0.080in.
Our assessment is: ANY ONE CAN BURN-UP ANY CLUTCH. Hard core riding with TOTALLY STOCK CLUTCH showed NO DAMAGE or signs of slippage at 155HP and only slight slippage at 200HP. The MPI Upgrade Kit eliminated the slippage at 200HP. However, we are not suggesting that some consumers will never have clutch problems. For our customers desiring a more heavy duty clutch, we recommend the MPI OEM Upgrade Pressure Plate Spring and Friction Plates Upgrade Kit.
