2006-2012 Honda TRX90 TRX90EX/X Service Manual, Page 107Get this manual
CYUNDER HEADVALVES Inspect the rocker arm shafts for wear or damageMeasure the rocker arm shaft .0 SERVICE LIMIT: 9.91 mm 10.390 in)
Calculate the rocker arm to shaft clearanceSERVICE LIMIT: 0.08 mm (0.003 in)
VALVE SPRING
Measure the free length of the inner and outer valve springsSERVICE LIMITS: Inner: 31 .2 mm (1.23 in) Outer: 34.0 mm (1.34 In)
Replace the springs if they are shorter than the service limits