430 / 1258
ENGINE
430
body
accessories
handlebar
& grips
cables &
levers
electrical
& ignition
engine
fuel &
intake
clutch
brakes
drive
steering &
suspension
bearings
tires
tools &
shop
exhaust
MODEL YEAR
BORE
X
STROKE
BORE
SIZE
TOP
END
KIT
SINGLE
PISTON RING SET PIN CLIP
TOP END
GASKET
KIT
TOP END
BEAR-
ING
YAMAHA (2-STROKE)
CONTINUED
YZ250
88-91 68
68
103949 605M06800 2677CD
S508
CW18 W5168 B1014
WR250
91
x
68.5
103950 605M06850 2697CD
*Power Valve must
be modified for
69mm and larger
*1991 model is
Nikasil bore
68
69
103951 605M06900 2717CD
69.5
102830
2736CD
70
103308
102831
2756CD
YZ250
92-98 68
68
736M06800 2677CS
S508
CW18 W5168 B1014
x
88-94
68
W5467
95-98
YZ250
92-94 68
68
101624 677M06800 2677CD
S508
CW18 W5168 B1014
WR250
92-94
x
68.5
101625 677M06850 2697CD
68
69
101626 677M06900 2717CD
70
102062
103107
2756CD
YZ250
95-98 68
68
103334 677M06800 2677CD
S508
CW18 W5467 B1014
WR250
95-98
x
68.5
103335 677M06850 2697CD
68
69
103336 677M06900 2717CD
70
103578
103107
2756CD
YZ250
99-01 66.4 66.4
101398 804M06640 2614CD
S508
CW18 W5744 B1003
x
68.5
102731 804M06850 2697CD
72
YZ250
02-16 66.4 66.4
101267 804M06640 2614CD
S508
CW18 W5978 B1003
YZ250X
16
x
67
101268 804M06700 2638CD
72
67.5
101269 804M06750 2658CD
68.5
101964 804M06850 2697CD
YZ250
02-16 66.4 66.4
102662 808M06640 104610
S508
CW18 W5978 B1003
YZ250X
16
x
72
YZ250
99-16 66.4
72
112196
111873
S508
CW18
B1003
*Note: Cylinder,
cylinder head, and
power valve modifi-
cations required
x
72
DT400
75-78 85
85
102825
104345
S277
CW18
B1003
MX400
75-76
x
85.5
102826
104346
70
86
102827
3386TD
86.5
101532
3405TD
IT400
77-78 85
85
112104
104345
S277
CW18
B1003
YZ400
77-78
x
85.5
101519
104346
70
86
101520
3386TD
86.5
103190
3405TD
87
112106
3425TD
IT465
81-82 85
85.5
101182
104346
S277
CW18
B1014
YZ465
80-81
X
86
101183
3386TD
82
86.5
103361
3405TD
IT490
83-84 87
87
103858
3425TD
S277
CW18 W4055 B1014
YZ490
82-83
x
87.5
103859
3445TD
1983
82
88
103860
3465TD
88.5
102411
104352
89
102412
3504TD
YZ490
84-90 87
87
103061 546M08700 3425TD
S277
CW18 W5286 B1014
WR500
92-93
x
87.5
103062 546M08750 3445TD
82
88
103063 546M08800 3465TD
88.5
102657
101228
104352
89
102658
101229
3504TD