Gearing; Assembly - Yamaha BR250F Service Manual

5. Inspect the drive chain; replace as neces-
sary.
6. Inspect the adjusting block. If the raised
boss is worn to the base of the block,
replace the block.
1 Wear limit 6 mm (0.24 in)
C. Gearing
Use the chart below to change the chain case
gearing to suit the local conditions and the
rider's driving style.
Higher gearing will increase the ma-
chine's top speed.
Lower gearing will increase the ma-
chine's acceleration and climbing ability.
Do not set the gearing to any of the indicated
(X) settings.
~
11T 12T 13T
14T
Driven gear
21T
X X
X
0
44
S.T.D.
22T
X X 0 X
44
23T
X
0
X X
44
24T
0
X
X X
*44
* No. of chain links
D. Assembly
1. Grease the inner surfaces of the bearings
and oil seals in the chain case.
2. Place the brake disc between the brake
pads. Be sure the raised side of the disc
faces away from the chain case.
3. Loosely bolt the chain case in place in
the chassis. It may be helpful to block
up the chassis to relieve the tension on
the drive axle.
4-12
4. Grease the bearing surfaces of the jack-
shaft. Place the key in the jackshaft, and
install the jackshaft from the left-side of
the machine. The splined end must go
through the brake disc and into the
chain case. Align the keyway in the
disc with the key on the jackshaft.
5. Tighten the chain case bolts and torque
them to specification.
Tightening torque:
2.3 m-kg (17 ft-Ib)
6. Install the jackshaft bearing on the left
side of the machine. Install the bearing
cage over the jackshaft bearing. Torque
the three bolts to specification.
Tightening torque:
2.3 m-kg (17 ft-lb)
7. Install the collar and the circlip into the
bearing cage.
8. Install both collars in the chain case. The
larger goes on the jackshaft, the smaller
on the drive axle.
9. Place both the drive and driven sprockets
in the drive chain, and install them in the
chain case. Be sure the stepped side of
the driven sprocket faces in towards the
engine.
10. Install the adjusting block.