Yamaha YZF-R125 Service Manual: Separating the crankcase
1. Remove:
- Crankcase bolts
NOTE:
Loosen each bolt 1/4 of a turn at a time, in stages and in the proper sequence as shown.
A. Right crankcase
B. Left crankcase
2. Turn:
- Shift drum segment
NOTE:
Turn the shift drum segment "1" to the position shown in the illustration. In this position, the shift drum segment teeth will not contact the crankcase during crankcase separation.
3. Remove:
- Right crankcase
| CAUTION: Tap on one side of the crankcase with a softface hammer. Tap only on reinforced portions of the crankcase, not on the crankcase mating surfaces. Work slowly and carefully and make sure the crankcase halves separate evenly. |
Crankcase
...
Checking the crankcase
1. Thoroughly wash the crankcase halves in a
mild solvent.
2. Thoroughly clean all the gasket surfaces and
crankcase mating surfaces.
3. Check:
Crankcase
Cracks/damage Replace.
Oil de ...
Other materials:
Checking the piston rings
1. Measure:
Piston ring side clearance
Out of specification Replace the
piston
and piston rings as a set.
NOTE:
Before measuring the piston ring side clearance,
eliminate any carbon deposits from the piston
ring grooves and piston rings.
2. Install:
Piston ring
(into the cylind ...
Checking the camshaft
1. Check:
Camshaft lobes
Blue discoloration/pitting/scratches
Replace
the camshaft.
2. Measure:
Camshaft lobe dimensions "a" and "b"
Out of specification Replace
the camshaft.
3. Check:
Camshaft oil passage
Obstruction Blow out with
compressed air. ...
Overheating
Engine
1. Clogged coolant passages
Cylinder head and piston
Heavy carbon buildup
2. Engine oil
Incorrect oil level
Incorrect oil viscosity
Inferior oil quality
Cooling system
1. Coolant
Low coolant level
2. Radiator
Damaged or leaking radiator
Faulty radiator cap
...