Cylinder Pistons

Cylinder Removal

Engine (see Engine Removal/Installation chapter) Cylinder Head (see Cylinder Head Removal) Water Hose

Front Camshaft Chain Guide

• Remove the cylinder.

Cylinder Installation

• Install the new cylinder gasket [A]. •Apply engine oil to the cylinder bore.

• Prepare two auxiliary head bolts with their head cut.

• Install the two bolts [B] diagonally in the crankcase.

[B] Auxiliary Head Bolts

[C] Pistons

Special Tools - Piston Ring Compressor Grip: 57001-1095

Piston Ring Compressor Belt, <J>67 ~ $79: 57001-1097

Piston Removal

• Remove the cylinder (see Cylinder Removal).

• Place a clean cloth under the pistons and remove the piston pin snap ring from the outside of each piston.

• Remove the piston pins.

Special Tool - Piston Pin Puller Assembly: 57001-910 [A]

• Remove the top and second rings with piston ring pliers. Special Tool - Piston Ring Pliers: 57001-115

• If the special tool is not available, carefully spread the ring opening with your thumbs and then push up on the opposit side of the ring [A] to remove it.

• Remove the 3-piece oil ring with your thumbs inthe same manner.

Piston Installation

• Do not mix up the top and second ring. O Install the top ring [A] so that the "R" mark [B] faces up. O Install the second ring [C] so that the "RN" mark [D] faces up.

•The piston ring openings must be positioned as shown in the figure. The openings of the oil ring steel rails must be about 30 - 40" of angle from the opening of the top ring.

[A] Top Ring [D] Oil Ring Expander

[C] Oil Ring Steel Rails

•The arrow on the piston head must point toward the front of the engine.

Do not reuse snap rings, as removal weakens and deforms them. They could fall out and score the cylinder wall.

Cylinder Wear

•Since there is a difference in cylinder wear in different directions, take a side-to-side and a front-to-back measurement at each of the two locations (total of four measurements) shown in the figure.

*lf any of the cylinder inside diameter measurements exceeds the service limit, the cylinder will have to be bored to oversize and then honed.

Cylinder Inside Diameter

Standard: 73.000 ~ 73.012 mm Service Limit 73.1 mm

Piston Wear

• Measure the outside diameter [A] of each piston 5 mm [B] up from the bottom of the piston at a right angle to the direction of the piston pin.

*lf the measurement is under service limit, replace the piston.

Piston Diameter

Standard: 72.942 - 72.958 mm

Service Limit: 72.8 mm


Piston Ring, Piston Ring Groove Wear

• Check for uneven groove wear by inspecting the ring seating.

*The rings should fit perfectly parallel to groove surfaces. If not, the piston must be replaced. •With the piston rings in their grooves, make several measurements with a thickness gauge [A] to determine piston ring/groove clearance.

Piston Ring/Groove Clearance

Standard Service Limit

Piston Ring End Gap

• Place the piston ring [A] inside the cylinder, using the piston to locate the ring squarely in place. Set it close to the bottom of the cylinder, where cylinder wear is low.

• Measure the gap [B] between the ends of the ring with a thickness gauge.

Piston Ring End Gap

Standard Service Limit

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