Yamaha YZF-R125 Service Manual: 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 head.
2. Loosen:
- Camshaft sprocket bolt "1"
NOTE:
While holding the generator rotor nut with a wrench "2", loosen the camshaft sprocket bolt.
3. Remove:
- Camshaft sprocket
NOTE:
To prevent the timing chain from falling into the crankcase, fasten it with a wire "1".
4. Remove:
- Cylinder head
NOTE:
- Loosen the bolts in the proper sequence as shown.
- Loosen each bolt 1/2 of a turn at a time. After all of the bolts are fully loosened, remove bolts 1, 2, 4, and 6, and then remove the cylinder head with bolts 3 and 5 installed in the bolt holes.
Cylinder head
* Yamaha bond No. 1215 (Three Bond No. 1215) ...
Checking the cylinder head
1. Eliminate:
Combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid damaging
or scratching:
Spark plug bore threads
Valve seats
...
Other materials:
Adjusting the exhaust gas volume
NOTE:
Be sure to set the CO density level to standard,
and then adjust the exhaust gas volume.
1. Remove:
Rider seat
Refer to "GENERAL CHASSIS" on page 4-1.
2. Set the main switch to "OFF".
3. Disconnect:
Self-diagnosis signal connector "1"
4. Connect:
FI diagnostic tool "2 ...
Checking the fuel sender
1. Drain the fuel from the fuel tank.
2. Check:
Fuel sender resistance
Out of specification → Replace the fuel
sender.
a. Connect the pocket tester ( ×
10) to the fuel
sender coupler as shown.
Positive tester probe
sky blue "1"
Negative tester probe
orange/white " ...
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 shown in the illustration.
4. Install:
Rocker arms
Rocker arm shafts "1"
NOTE:
Make ...