YACUGAR, THUNDERHILL RACEWAY PARK
TEMP: 73F ambient, surface at 98F
BIKE:Â 2009 Yamaha R1, 5,800 miles on the odometer
lap 1 straight line braking and acceleration
lap 2 trail braking and mid corner throttle
lap 3 corner exit acceleration
lap 4, fast lap at 90%
Once the 6 laps were completed, the in lap was the same pace as lap 6. The pressure gauge was calibrated earlier to ensure accuracy. Upon entering the hot pit, the bike was parked quickly and hot pressure set at 36 psi front and 25psi rear.
Session 2: (started immediately after tire pressure was set, total 8 laps)
The goal of session 2 was to evaluate shock response under hard acceleration and Turn 6 was the focus point for the test. It was immediately obvious that the rear of the bike would squat too much so we needed to determine if this was due to preload or ride height. Two turns of ride height were added then removed and 3 clicks of low speed were added and removed. A compromise setting of 1 turn of ride height and 2 clicks of low speed compression were found to provide the best result to eliminate the squat.
Session 3: (started immediately, total 8 laps)
The goal of session 3 was to assess mid corner stability and turn 2 was the corner of choice. Entry speed was a little too fast allowing the front tire to scrub speed, but the throttle was set for a constant radius arc to assess handlebar action side to side/rowing. After a couple of passes through turn 2. Rebound was too slow causing the handlebar to row gently side to side. Rebound was changed 1 click at a time and settled at 23 out for perfectly stable handle bars.
However, changes needed to be made especially with the high speed bumps in 2, 5 and 9 and high speed damping changes shock changes went from 15 to 19 clicks out.
During this session we had the beginnings of rear tire tear: The rear tire was showing initial faint tearing where the bulk of the power was being laid down exiting corners, not where neutral throttle was being applied.
BREAK TIME for hydration, recollection of thoughts and accurate note taking â€“ 15 minutes
Session 4: (2 warm up laps on the tires and 8 fast laps;- total 10 laps)
The goal of session 4 was to ascertain the source of the rear tire wear and correct it.
BREAK for shock removal and 5mm spacer insertion (took lunch) leaving the shock at stock length of 295mm.
The bike was raised on foot peg stands and the top shock mount bolt loosened with a 23m wrench. The rear stand was used to support the swing arm as the clevis nut was removed and the top shock bolt removed. Spacers were placed on top of the OEM spacer, making a total ride height change ofÂ +5mm. The shock was secured, all nuts and bolts tightened and everything double checked. Forks remained in the same position as a control.
Session 5: (2 warm up laps on the tires and 8 fast laps;- total 10 laps)
The goal of session 5 was to run a complete session with no stops to see if the rear tire would clean up under duress. Pace was constant at the 2:00 to 2:01 lap times to ensure consistency of rider inputs at all times.
The rear tire wear completely cleaned up.
Session 6: (total 15 laps)
The goal of session 6 was to ride the bike at an increasingly faster pace (fastest lap a 1:58), using the same testing criteria as in earlier sessions to assess braking/steering, mid corner stability and corner exit drive. In running a high number of consecutive laps that would also allow me to get a great feel for the carcass movement under all skill execution conditions.
At the end of the 15 laps, the rear tire wear was perfect!
Free sag at 8mm
Shock length at 295mm plus 5mm spacer
Preload at line # 6
Low speed compression at 15 clicks out
High speec compression at 19 clicks out
Rebound at 23 clicks out
the shock is highly adjustable but over 2 clicks you can really feel a difference so the needle taper is excellent for having changes manifest themselves quickly in the hydraulics
base line valving is excellent for high and low speed:- changes made suggest that high speed may be slightly over valved but still well in range
hydraulic adjuster is a little difficult to use with not much room for the hand and fingers to access the dial especially when hot
shock did not fade at all throughout the entire day even on long stints
For the testing period, that was 57 laps x 3 miles = 210 miles.
The rear tire was run another 140 miles and then flipped and run another 170 miles for a total of 520 miles before the tire was replaced. No settings were changed in the shock and tire wear remained the same so the shock hydraulics did not fade when the shock got hot!
Very impressed with the shock especially in regards to valving and how a couple of clicks provide a profound difference in healing tires and in how the shock maintains its level of performance with no fade even on long runs of consecutive laps and after 520 miles.
- the shock now has 2,000 miles on it and the settings have not changed.!