Yamaha DT175MX
Checking Cylinder, Piston, Rings and Crankshaft
Piston rings end gap (Both rings) 0.3 – 0.5mm
Ring groove side clearance, Top 0.02 – 0.06mm, 2nd 0.03 – 0.07mm
Cylinder maximum taper 0.05mm (0.02in)
Cylinder maximum out of round 0.01mm (0.04in)
Piston clearance: Using an outside micrometer, measure piston diameter. The only core measuring point is at right angles to the piston pin holes and about 10mm from the bottom of the piston. Compare piston diameter to cylinder bore measurements.
Piston clearance is Minimum cylinder diameter minus maximum piston diameter.
Min 0.035mm, Max 0.04mm
Piston pin and bearing, Apply a light film of oil to pin and bearing surfaces. Install in connecting rod small end to inspect for wear. There should be no noticeable vertical play. If play exists check connecting rod small end for wear. Replace pin, connecting rod and/or bearing as required.
Connecting rod Cylinder Specs
Con rod axial ( C )
New 0.8 – 1.0mm , Maximum 2mm
Con rod side ( D ) Big end clearance
Min 0.02mm (0.008in), Max 0.8mm (0.03in)
...Paul