Kawasaki STX-15F service manual Cylinder Wear, Piston Wear, Piston Ring, Piston Ring Groove Wear

6-34 ENGINE TOP END

Cylinder, Pistons

Cylinder Wear

•Since there is a difference in cylinder wear in different di- rections, take a side-to-side and a front-to-back measure- ment at each of the two locations (total of four measure- ments) shown in the figure.

If any of the cylinder inside diameter measurements ex- ceeds the service limit, replace the cylinder.

[A]10 mm (0.39 in.)

[B]60 mm (2.36 in.)

Cylinder Inside Diameter

Standard:	82.994 ∼ 83.006 mm (3.2675 ∼ 3.2679 in.)
Service Limit:	83.10 mm (3.272 in.)

Piston Wear

•Measure the outside diameter [A] of each piston 18 mm (0.71 in.) [B] up from the bottom of the piston at a right angle to the direction of the piston pin.

If the measurement is less than the service limit, replace the piston.

Piston Diameter	82.919 ∼ 82.934 mm (3.2645 ∼ 3.2651 in.)
Standard:

Service Limit: 82.77 mm (3.259 in.)

Piston Ring, Piston Ring Groove Wear

•Checking. for uneven groove wear by inspecting the ring seat-

The rings should fit perfectly parallel to groove surfaces. If not, replace the piston and all the piston rings.

•With the piston rings in their grooves, make several mea- surements with a thickness gauge [A] to determine piston ring/groove clearance.

Piston Ring/Groove Clearance
Standard:
Top	0.03 ∼	0.07 mm (0.0012 ∼	0.0028 in.)
Second	0.02 ∼	0.06 mm (0.0008 ∼	0.0024 in.)
Service Limit:
Top	0.17 mm (0.0067 in.)
Second	0.16 mm (0.0063 in.)

Piston Ring Groove Width

•Measure the piston ring groove width.

○Use a vernier caliper at several points around the piston.

Standard:

Top [A] 0.92 ∼ 0.94 mm (0.0362 ∼ 0.0370 in.) Second [B] 1.01 ∼ 1.03 mm (0.0398 ∼ 0.0406 in.)

Service Limit:

Top [A] 1.02 mm (0.0402 in.) Second [B] 1.11 mm (0.0437 in.)

If the width of any of the two grooves is wider than the service limit at any point, replace the piston.