Valve Shim Calculator for the CRF150R - CRF250R/X/RX/L - CRF300L - CRF450R/X/RX/L/RL

Honda CRF Motorcycle Valves and Shims

• Always use a micrometer to measure your valves and shims.
• Use the inches to millimeter conversion tool on this page if your micrometer is not metric.
• We have 73 different thickness of shims from 1.200mm to 3.000mm in intervals of 0.025mm.
• Reface the valve seat if carbon deposit result in a calculated dimension of over 3.000mm.
• Honda CRF150R, CRF250R/X/RX/L, CRF300L require 7.48mm OD shims and Honda CRF450R/X/RX/L/RL require 9.48mm OD shims
• Download our CRF250 Valve Shim Calculator Excel spreadsheet
• Download our CRF450 Valve Shim Calculator Excel spreadsheet