The URGE designs S1000 RR Superbike cams ~15% increase in valve lift is beyond OEM valve spring specifications limiting valve control at high RPM and potentially catastrophically damaging the motor.  The Carpenter Racing valve spring kit utilizes a ~20% larger diameter, surface treatment enhanced, single spring design reducing valve spring weight and inertial while increasing valve lift support and maintaining long life.  Additionally, the Carpenter Racing kit uses the strongest and hardest Titanium Ti-17 alloy retainers, eliminating issues seen on common Titanium alloy retainers.  Finally, the Carpenter Racing valve spring kit utilizes OEM keepers and intake spring bases in an effort to reduce cost compared to competing high end kits.  The Carpenter Racing valve spring and retainers have been proven across several literbike applications to control superbike valve lifts and provide longevity.

Single Spring

A key design element is using a single valve spring for both intake and exhaust (OEM use dual valve springs on the intake side).  Single valve springs have less overall mass than dual springs reducing spring momentum and stresses supporting higher RPM.  The Carpenter Racing single valve spring weighs 27 grams vs the OEM dual intake and single exhaust springs weight 36 and 37 grams respectively.  This is a weight savings of  ~25% supporting higher RPMs.

Even though the OEM exhaust utilizes a single valve spring, it is thinner and weaker spring than the Carpenter Spring that requires more coils increasing weight beyond the OEM intake dual valve springs.

The Carpenter Racing Valve Spring kit uses the highest quality Chrome Silicon Vanadium (CrSiV) alloy with a ~20% thicker wire diameter at 3.6mm vs 3mm for the OEM intake main spring and 3.1 for the OEM exhaust spring.   The thicker and stronger spring reduces the number of coils allowing for higher valve lift and improved valve control at higher RPM.

Carpenter Racing Single Valve Spring (left), OEM intake dual valve spring (center) and OEM exhaust single valve spring (right)

There is a market myth that dual valve springs are more reliable than single springs as each spring can act as a backup in case one of them fails.  This is false as each individual spring in a dual spring kit is designed to provide part of the pressure needed to support the valve at higher RPM.  So, if one spring does fail, the other will either quickly fail or the valve will begin to float and fail due to piston to valve or valve to valve contact.

Spring Endurance Enhancements

In addition to supporting higher valve lift and redline, the Carpenter Racing valve springs also improve endurance.  Many aftermarket spring pressures will degrade over time with high intensity use at high RPM or on track, thus could be considered a maintenance item that needs to be replaced periodically. The Carpenter Racing Valve springs are shot peened, and heat treated to reduce surface and internal stresses created during the spring manufacturing process.  This stress can grow during high intensity usage degrading spring pressure or ultimately lead to failure.  The Carpenter Racing Valve Spring surface treatment have proven to maintain full spring pressure with high repetitive and intensity usage.

Valve Spring Retainer Material

Another myth on the market is that Titanium retainers are not strong or tough enough to survive high lift and RPM as other spring kits have exhibited high wear and or bending.  Several manufactures even designate their Titanium retainers as a maintenance item that should be replaced often.

The Carpenter Racing Valve Spring kit uses Ti-17 alloy which is the strongest commonly used titanium alloy with ~30% higher yield strength than the typically used 6Al4V alloy.  Ti-17 also has a higher surface hardness of HRC 40 vs 6Al4V HRC 33 eliminating surface wear concerns.  Ti-17 is also ~10% stronger than quenched chromoly 4140 steel used for many steel spring retainers.

If you are still not convinced about Ti-17, it is the Titanium alloy used in turbofan blades, one of the highest stressed environments that has zero room for failure.