CYLINDER AND PISTON

ENG

Piston pin

1.Inspect:

Piston pin

Blue discoloration/grooves Replace, then inspect the lubrication system.

2.Measure:

Piston pin-to-piston clearance

Measurement steps:

Measure the outside diameter (piston pin) a.

If out of specification, replace the piston pin.

Outside diameter (piston pin): 17.991 ~ 18.000 mm (0.7083 ~ 0.7087 in)

Measure the inside diameter (piston) b.

Inside diameter (piston): 18.004 ~ 18.015 mm (0.7088 ~ 0.7093 in)

Calculate the piston pin-to-piston clear- ance with the following formula.

Piston pin-to-piston clearance = Inside diameter (piston) b – Outside diameter (piston pin) a

If out of specification, replace the piston.

Piston pin-to-piston clearance: 0.004 ~ 0.024 mm

(0.00016 ~ 0.00094 in) <Limit>: 0.07 mm (0.003 in)

ASSEMBLY AND INSTALLATION Piston

1.Install:

Piston rings Onto the piston.

NOTE:

Be sure to install the piston rings so that the manufacturer’s marks or numbers are located on the upper side of the rings.

Lubricate the piston and piston rings liberally with engine oil.

4 - 46

Page 169
Image 169
Yamaha WR45OFR service manual Piston pin, Inside diameter piston 18.004 ~ 18.015 mm 0.7088 ~ 0.7093