JT Sprockets

Online Catalogue

KTM 400 SX Motocross — USA

1998

Front Sprocket

Steel Front Sprocket

Part Number: JTF1902

Teeth: 14

Available Sizes: 12, 13, 14, 15, 16, 17

OE Type Rubber Cushioned Front Sprocket

Part Number: JTF1902RB

Teeth: 14 Check Availability

Available Sizes: 15, 16, 17

Rear Sprocket

Lightweight Self-Cleaning Rear Sprocket

Part Number: JTR897SC

Teeth: 45

Available Sizes: 40, 42, 45, 48, 49, 50, 51, 52

Steel Rear Sprocket

Part Number: JTR897

Teeth: 45

Available Sizes: 38, 40, 41, 42, 44, 45, 46, 47, 49, 50, 52, 53

Racelite Aluminium Rear Race Sprocket

Part Number: JTA897BLK

Teeth: 45

Available Sizes: 38, 40, 41, 42, 45, 47, 48, 49, 50, 51, 52

Drive Chain

Pitch: 520

Length: 118

Please note that the chain shown in this listing is for size reference only. For the correct chain type and grade, please refer to the vehicle's manufacturer manual.

Gear Ratio Chart

TeethFront Sprocket
14151617
Rear Sprocket382.71
-15.6%
2.53
-21.2%
2.38
-26.1%
2.24
-30.5%
402.86
-11.1%
2.67
-17.0%
2.50
-22.2%
2.35
-26.8%
412.93
-8.9%
2.73
-15.0%
2.56
-20.3%
2.41
-25.0%
423.00
-6.7%
2.80
-12.9%
2.62
-18.3%
2.47
-23.1%
443.14
-2.2%
2.93
-8.7%
2.75
-14.4%
2.59
-19.5%
453.21
standard
3.00
-6.7%
2.81
-12.5%
2.65
-17.6%
463.29
+2.2%
3.07
-4.6%
2.88
-10.6%
2.71
-15.8%
473.36
+4.4%
3.13
-2.5%
2.94
-8.6%
2.76
-14.0%
493.50
+8.9%
3.27
+1.6%
3.06
-4.7%
2.88
-10.3%
503.57
+11.1%
3.33
+3.7%
3.12
-2.8%
2.94
-8.5%
523.71
+15.6%
3.47
+7.9%
3.25
+1.1%
3.06
-4.8%
533.79
+17.8%
3.53
+9.9%
3.31
+3.1%
3.12
-3.0%

Lower gear ratios allow for higher top speeds.

Higher gear ratios increase torque for better acceleration.

Full Gear Ratio Chart (pdf)