The R&D Racing Power Spring increases throttle response by eliminating the lag caused by hydraulic resistance in the accelerator pump.  During periods of fast throttle actuation the gas in the accelerator pump reservoir provides a hydraulic resistance that causes the pump to lag slightly behind the throttle.  This results in a temporary lean condition and throttle lag.  The R&D Racing Power Spring prevents this by applying more pressure to keep the pump actuating mechanism locked in place with the throttle mechanism.


Made from high quality stainless steel the spring will not corrode or break over time.  Some "hot fixes" for this issue will become brittle in cold weather or become cracked and break over time.  Install the Power Spring once and forget about it for good!

This spring will work on all aftermarket Keihin FCR and FCR-MX carburetors.  It also works on all Keihin FCR-OEM carburetors found on many popular off-road OEM machines from Honda, Kawasaki, Suzuki, and Yamaha.