Yamaha YZF-R125 Service Manual: Checking the drive chain

Yamaha YZF-R125 Service Manual / Chassis / Chain drive / Checking the drive chain

1. Measure:

15-link section "a" of the drive chain Out of specification Replace the drive chain.

a. Measure the length "a" between the inner sides of the pins and the length "b" between the outer sides of the pins on a 15-link section of the drive chain as shown in the illustration.

Checking the drive chain

b. Calculate the length "c" of the 15-link section of the drive chain using the following formula.

Drive chain 15-link section length "c" = (length "a" between pin inner sides + length "b" between pin outer sides)/2

NOTE:

When measuring a 15-link section of the drive chain, make sure that the drive chain is taut.
Perform this procedure 2-3 times, at a different location each time.

Checking the drive chain

2. Clean:

Drive chain

a. Wipe the drive chain with a clean cloth.

b. Put the drive chain in kerosene and remove any remaining dirt.

c. Remove the drive chain from the kerosene and completely dry it.

CAUTION:

This motorcycle has a drive chain with small rubber O-rings "1" between the drive chain side plates. Never use high-pressure water or air, steam, gasoline, certain solvents (e.g., benzine), or a coarse brush to clean the drive chain. High-pressure methods could force dirt or water into the drive chain's internals, and solvents will deteriorate the O-rings. A coarse brush can also damage the O-rings. Therefore, use only kerosene to clean the drive chain.
Do not soak the drive chain in kerosene for more than ten minutes, otherwise the Orings can be damaged.

Checking the drive chain

3. Check:

O-rings "1" Damage Replace the drive
chain.
Drive chain rollers "2" Damage/wear Replace the
drive chain.
Drive chain side plates "3" Damage/wear Replace the drive
chain.

Cracks Replace the drive
chain.

Checking the drive chain

4. Lubricate:

Drive chain

Chain drive

Removing the drive chain 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 ...

Checking the drive sprocket

1. Check: Drive sprocket More than 1/4 tooth "a" wear Replace the drive chain sprockets as a set. Bent teeth Replace the drive chain sprockets as a set. b. Correct 1. Dri ...

Other materials:

Installing the shift shaft
1. Install: Stopper lever "1" Stopper lever spring "2" NOTE: Install the stopper lever spring as shown in the illustration. Hook the ends of the stopper lever spring onto the stopper lever and the crankcase boss "3". Mesh the stopper lever with the shift drum segment assembly. ...

Checking the primary drive gear
1. Remove: Primary drive gear Refer to "BALANCER GEAR" on page 5-53. 2. Check: Primary drive gear Damage/wear Replace the primary drive gear and clutch housing as a set. Excessive noise during operation Replace the primary drive gear and clutch housing as a set ...

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 ...