2008 Polaris ATV Sportsman 300 400 H.O. Service Manual, Page 66Get this manual
ENGINE (300) 5Measure diameter of valve stem with micrometer in three places and in two different directions (six measurements total)Replace if excessive wear is evidentMeasure valve stem in several places Cylinder Head Reconditioning NOTE: Servicing the valve guides and valve seats requires special tools and thorough knowledge of reconditioning techniques
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