Yamaha YZF-R125 Service Manual: Lubricating the drive chain
The drive chain consists of many interacting parts. If the drive chain is not maintained properly, it will wear out quickly. Therefore, the drive chain should be serviced, especially when the vehicle is used in dusty areas.
This vehicle has a drive chain with small rubber O-rings between each side plate. Steam cleaning, high-pressure washing, certain solvents, and the use of a coarse brush can damage these O-rings. Therefore, use only kerosene to clean the drive chain. Wipe the drive chain dry and thoroughly lubricate it with engine oil or chain lubricant that is suitable for O-ring chains.
Do not use any other lubricants on the drive
chain since they may contain solvents that could
damage the O-rings. 
Adjusting the drive chain slack
NOTE:
The drive chain slack must be checked at the
tightest point on the chain.
CAUTION:A drive chain that is too tight will
overload
the engine and other vital parts, and one that
...
Checking and adjusting the steering head
1. Stand the vehicle on a level surface
WARNINGSecurely support the vehicle so that there
is
no danger of it falling over.
NOTE:
Place the vehicle on a suitable stand so that the ...
Other materials:
Checking the shift forks
The following procedure applies to all of the shift
forks.
1. Check:
Shift fork cam follower "1"
Shift fork pawl "2"
Bends/damage/scoring/wear
Replace the
shift fork.
2. Check:
Shift fork guide bar
Roll the shift fork guide bar on a flat surface.
Bends Replace. ...
Unstable handling
Handlebars
- Bent or improperly installed right handlebar
- Bent or improperly installed left handlebar
1. Steering head components
- Improperly installed upper bracket
- Improperly installed lower bracket
(improperly tightened ring nut)
- Bent steering stem
- Damaged ball bearing or bearing ...
Chassis tightening torques
NOTE:
First, tighten the lower ring nut to approximately 48 Nm (4.8 m.kg,
35 ft.lb) with a torque wrench, then
loosen the lower ring nut completely.
Retighten the lower ring nut to 13 Nm (1.3 m.kg, 9.4 ft.lb) with a
torque wrench.
...