Yamaha YZ250FM 2021 Owner's Service Manual

CAMSHAFT5-17EAM30081CHECKING THE CAMSHAFT1. Check:• Camshaft lobeBlue discoloration/pitting/scratches  Re-place the camshaft.2. Measure:• Camshaft lobe dimensions “A”Out of specification  Replace the camshaft.3. Measure:• Camshaft-journal-to-camshaft-cap clearanceOut of specification  Measure the camshaftjournal diameter.a. Install the camshaft into the cylinder head.b. Position a strip of Plastigauge® “1” ontothe camshaft journal as shown.c. Install the dowel pins and the camshaftcaps.TIP• Tighten the camshaft cap bolts in a crisscrosspattern from innermost to outer caps.• Do not turn the camshaft when measuring thecamshaft journal-to-camshaft cap clearance.d. Remove the camshaft caps and then mea-sure the width of the Plastigauge® “1”.4. Measure:• Camshaft journal diameter “a”Out of specification  Replace the camshaft.Within specification  Replace the cylinderhead and the camshaft caps as a set.Camshaft lobe dimensionsLobe height limit (Intake)32.130 mm (1.2650 in)Lobe height limit (Exhaust)33.460 mm (1.3173 in)Camshaft-journal-to-camshaft-cap clearance0.028–0.062 mm (0.0011–0.0024in)222 1133Camshaft cap bolt10 N·m (1.0 kgf·m, 7.4 lb·ft)Camshaft journal diameter21.959–21.972 mm (0.8645–0.8650 in)111T R..111