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:
Supporting the motorcycle
Since this model is not equipped with a
centerstand, follow these precautions
when removing the front and rear
wheel or performing other maintenance
requiring the motorcycle to stand upright.
Check that the motorcycle is in a
stable and level position before starting
any maintenance. A ...
Cable routing
Front brake light switch lead
Right handlebar switch lead
Throttle cable
Main switch
Clutch cable
Clutch switch lead
Left handlebar switch lead
Sub-wire harness
Horn
Speed sensor lead
Front brake hose
Main switch lead
Left headlight assembly lead
Right headlight asse ...
Installing the exhaust assembly
1. Install:
Exhaust assembly "1"
Exhaust pipe nuts "2"
Exhaust assembly bolts "3" "4"
NOTE:
Do not fully tighten the nuts and bolts.
2. Tighten:
Exhaust pipe nuts "2"
Exhaust assembly bolt "4"
Exhaust assembly bolt "3"
...