Yamaha YFM250XL(C) Service Manual page 198

6
MIDDLE GEAR SERVICE
In the example above, the calculated shim
thickness is 0.57 mm. The chart instructs
you, however, to round off the 7 to 5, then
shim thickness is 0.55 mm.
Shim selection ı
When the crankcase and/or the driven pin-
ion gear are replaced, be sure to adjust
the driven pinion gear shim ı.
To find driven pinion gear shim thickness
"B" use following formula:
Driven pinion gear shim thickness:
ı = c – d – e – f
c= The stamped number on the crankcase
is added to from "110".
d= The stamped number on the crankcase
is substracted from "59".
e= Bearing (driven pinion gear) thickness
(considered constant) "13.00 mm".
f= The stamped number on the driven
pinion gear is added to or substracted
from "37.5".
Example:
1) If the drive pinion gear is stamped "45"
..... c = 110 + 0.45 = 110.45
2) If the crank case is stamped "–02"
..... d = 59 - 0.02 = 58.98
3) If the driven pinion gear is stamped
"+02"
..... f = 37.5 + 0.02 = 37.52
4) Therefore, shim thickness ı is,
ı = 110.45 – 58.98 – 13.00 – 37.52 =
0.95 mm
5) Shim sizes are supplied in following
thickness:
Thickness (mm)
Because shims can only be selected in 0.05
mm increments, round off hundredths digit
and select appropriate shim(s).
6 - 12
DRIV
Drive pinion gear
shim
0.15 0.40
0.20 0.50
0.30