Yamaha YZF-R125 Service Manual: Valves and valve springs

Installing the camshaft and rocker arms

1. Lubricate: Rocker arms Rocker arm shafts 2. Lubricate: Camshaft 3. Install: Camshaft "1" NOTE: Make sure that the camshaft projections "a" and hole "b" are positioned as s ...

Removing the valves

The following procedure applies to all of the valves and related components. NOTE: Before removing the internal parts of the cylinder head (e.g., valves, valve springs, valve seats), make sure th ...

Other materials:

Removing the cylinder head
1. Align: "I" mark "a" on the generator rotor (with the stationary pointer "b" on the generator cover) a. Turn the crankshaft counterclockwise. b. When the piston is at TDC on the compression stroke, align the "I" mark "c" on the camshaft sprocket with the mark "d" on the cylinder h ...

Troubleshooting charts
Starting problems or poor engine performance Starting problems or poor engine performance Engine overheating WARNING Do not remove the radiator cap when the engine and radiator are hot. Scalding hot fluid and steam may be blown out under pressure, which could cause serious injury. Be ...

Checking the valve seats
The following procedure applies to all of the valves and valve seats. 1. Eliminate: Carbon deposits (from the valve face and valve seat) 2. Check: Valve seat Pitting/wear Replace the cylinder head. 3. Measure: Valve seat width C "a" Out of specification Replace the ...