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:
Checking the starter motor
1. Check:
Commutator
Dirt Clean with 600 grit
sandpaper.
2. Measure:
Commutator diameter "a"
Out of specification Replace
the starter
motor.
3. Measure:
Mica undercut "a"
Out of specification Scrape
the mica to the
proper measurement with a hacksaw blade
...
Removing the throttle body
1. Extract the fuel in the fuel tank through the
fuel tank filler hole with a pump.
2. Disconnect:
Fuel hose
WARNINGCover the fuel hose connections with a
cloth
when disconnecting them. Residual pressure
in the fuel lines could cause fuel to
spurt out when removing the h ...
Installing the shift forks and shift drum assembly
1. Install:
Shift fork-L "1"
Shift fork-C "2"
Shift fork-R "3"
Shift drum assembly "4"
Springs
Shift fork guide bar "5"
NOTE:
The embossed marks on the shift forks should
face towards the right side of the engine and be
in the following sequence: "R", "C", "L".
2. Check:
Tr ...