Blue Line Brake Sight Lens Replacement 18mm | GY6 139QMB
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Keep your brake fluid level visible and your system sealed with the Blue Line Brake Master Cylinder Sight Lens. This OEM-equivalent replacement lens fits the stock brake master cylinder on 139QMB and GY6-based scooters, and includes an o-ring gasket for a leak-free seal.
Key Features
- OEM Equivalent: Direct-fit replacement for stock brake master cylinders on QMB and GY6 engines.
- Includes O-Ring Gasket: Everything needed for a complete, leak-free installation.
- Wide Compatibility: Fits 50cc through 169cc engines with QM or FM engine codes.
- Affordable Maintenance: Restore brake fluid visibility without replacing the entire master cylinder.
Technical Specifications
- Lens Outer Diameter: 18mm
- Includes: Sight lens + o-ring gasket
- SKU: 1000-1378
Engine Compatibility
139QMB-based 50cc / 80cc engines:
| 139QMA | 139QMB | 1P39QMB | 1P39QMA-2 |
| YN139QMB | JJ1P39QMB | 139FMA-2 | BD1P39QMB |
| BN139QMB | 147QMD | Other QMA models | Other QMB models |
157QMJ-based 125cc / 150cc / 169cc engines:
| 157QMJ | 161QMK | 152QMI | 1P61QMK |
| YN1P57QMJ | 1P52FMI | 154FMI | JJ157QMJ |
| 1P57QMJ | BN157QMJ | BN161QMK-A | Other QMJ, QMK, QMI models |
Tip: Don't see your engine listed? If your engine code includes "QM" or "FM", this lens is compatible with your vehicle.
Shipping information
Orders are prepared as quickly as possible. Delivery times and shipping costs are calculated at checkout based on the destination and items ordered.
Returns & warranty
Please verify fitment and part number before ordering. Contact Thrifty Scooters promptly if an item arrives damaged or incorrect.