Ready Racing (9501R4 R4 Rapid Response Accelerator Pump to Throttle Linkage System R4 replaces your existing standard linkage system that connects to your accelerator pump inside your carb with Ready Racing's new patent pending linkage technology R4's design allows for immediate rapid throttle response, eliminating 4 stroke hesitation/bog, and reducing hot engine stalling Ideal in conditions that require precise throttle response Bolt-on product that requires no modification Fits: Honda CRF250/450R/X 02-06, CRF150R 07; Kawasaki KX450F 05-09, KX250F 05-09; KTM SXF250/450 03-09, XC/EXC450/525 03-09; Suzuki RM-Z450 05-07, RM-Z250 04-09; Yamaha YZ250/450F 03-09