1998 Cobra BM50 Dirt Bike Torque Specs
Shop parts for a 1998 Cobra BM50 Dirt Bike.
The 1998 Cobra BM50 continues the 50cc youth motocross machine into its fifth production year with updated graphics and component improvements. The air-cooled 50cc two-stroke single in Cobra’s youth chassis serves a competitive role for riders building the fundamental motocross skills they will carry through larger displacement classes. Regular maintenance with correct torque values protects aluminum threads and lightweight components that are not interchangeable with common parts-bin hardware as the machine ages. Pre-race checks of handlebar clamp bolts at 8 Nm and axle nuts at 25 Nm (rear) should become routine before every moto.
Engine Torque Values
| Fastener | Torque (Nm) | Torque (ft-lbs) |
|---|---|---|
| Spark Plug | 12 | 9 |
| Cylinder Head Nuts | 8 | 6 |
| Cylinder Base Nuts | 8 | 6 |
| Flywheel/Rotor Nut | 25 | 18 |
| Clutch Hub Nut | 20 | 15 |
| Exhaust Flange Nuts | 8 | 6 |
Chassis & Suspension
| Fastener | Torque (Nm) | Torque (ft-lbs) |
|---|---|---|
| Swingarm Pivot Bolt | 20 | 15 |
| Fork Clamp Bolts | 8 | 6 |
| Handlebar Clamp Bolts | 8 | 6 |
| Shock Upper Mount | 15 | 11 |
| Shock Lower Mount | 15 | 11 |
| Subframe Bolts | 10 | 7 |
| Engine Mount Bolts | 15 | 11 |
Wheels & Drivetrain
| Fastener | Torque (Nm) | Torque (ft-lbs) |
|---|---|---|
| Front Axle Nut | 15 | 11 |
| Rear Axle Nut | 25 | 18 |
| Rear Sprocket Nuts | 12 | 9 |
| Chain Adjuster Lock Nuts | 8 | 6 |
Brakes
| Fastener | Torque (Nm) | Torque (ft-lbs) |
|---|---|---|
| Front Caliper Bolts | 10 | 7 |
| Rear Caliper Bolts | 10 | 7 |
| Disc Bolts | 6 | 4 |
Youth Bike Torque Notes
Premix two-stroke — no oil drain plug. 1/4-inch drive wrench required for all engine hardware. Fifth-year machines may have thread wear on heavily serviced fastener points; inspect carefully before final torque.
Thread Locker Application
- Rear sprocket nuts
- Disc bolts
- Subframe bolts
- Exhaust flange nuts
Torque Wrench Selection
A 1/4-inch drive click-type wrench is the only appropriate tool for the BM50’s small fastener architecture. Consistent use prevents the cumulative thread damage that comes from repeated hand-tightening on aluminum.
Related Shopping Categories
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Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.