Service manual
Table Of Contents
- Inroduction
- Yamaha Motor Corporation, USA YZ/WR Motorcycle Limited Warranty
- How to use this Manual
- Index
- Contents
- Chapter 1 General Information
- Chapter 2 Specifications
- Chapter 3 Regular Inspection and Adjustments
- Chapter 4 Engine
- Seat, Fuel Tank and Side Covers
- Exhaust Pipe and Silencer
- Radiator
- Carburetor and Reed Valve
- Cylinder Head, Cylinder and Piston
- Clutch and Primary Driven Gear
- Kick Axle, Shift Shaft and Primary Drive Gear
- YPVS Govenor
- Water Pump
- CDI Magneto
- Engine Removal
- Crankcase and Crankshaft
- Transmission, Shift Cam and Shift Fork
- Chapter 5 Chassis
- Chapter 6 Electrical
- Chapter 7 Tuning
4-20
ENG
CYLINDER HEAD, CYLINDER AND PISTON
EC474000
INSPECTION
EC474102
Cylinder head
1. Eliminate:
9
Carbon deposits
Use a rounded scraper 1.
NOTE:
Take care to avoid damaging the spark plug
threads. Do not use a sharp instrument. Avoid
scratching the aluminum.
2. Inspect:
9
Cylinder head water jacket
Crust of minerals/Rust → Remove.
9
Cylinder head warpage
Out of specification → Re-surface.
Warpage measurement and re-surface-
ment steps:
9
Attach a straightedge 1 and a thickness
gauge 2 on the cylinder head.
9
Measure the warpage.
9
If the warpage is out of specification, resur-
face the cylinder head.
9
Place # 400~600 grit wet sandpaper 3 on
the surface plate, and re-surface the head
4 using a figure-eight sanding pattern.
NOTE:
Rotate the cylinder head several times to
avoid removing too much material from one
side.
EC474201
Cylinder
1. Eliminate:
9
Carbon deposits
Use a rounded scraper 1.
NOTE:
Do not use a sharp instrument. Avoid scratching
the aluminum.
Warpage limit:
0.03 mm(0.0012 in)
1C3-28199-10 109 04.5.17, 9:22:07 PM