Yuasa Motorbike battery YTX5L-BS / YTX5L 12V 4Ah (4,2Ah) (AGM maintenance-free)

The Yuasa YTX5L-BS (or YTX5L as a factory-filled version) is a widely used AGM battery for scooters in the 80-125cc class as well as for sports enduros. It shares the footprint with the smaller YTX4L but is built higher to hold more lead plates. With a capacity of 4 Ah (10h) or 4.2 Ah (20h) and a cold cranking current of 80 A (EN), it provides around 30% more energy than the smaller 3Ah model, making it the standard choice for many 4-stroke scooters and competition enduros.

Highlights at a glance

• The standard for 125cc & enduros: Very frequently used in 4-stroke scooters (e.g. Honda Lead, Peugeot Speedfight 100) and almost all KTM EXC-F 4-stroke enduros.
• Compact power format: Uses the small footprint (114 x 71 mm) but offers considerably more starting reserves than the flatter YTX4L because of its height of 106 mm.
• AGM technology: The acid is bound in the glass fleece, making the battery leak-proof and extremely vibration-resistant – essential for enduros in tough off-road use.
• Maintenance-free: Thanks to VRLA (valve-regulated) technology, the system is hermetically sealed after first filling; topping up with water is not possible and not required.
• Solid starting power: With 80 A cold cranking current it reliably starts single-cylinder engines up to approx. 250cc (4-stroke) or 125cc (2-stroke).
• Position independence: Can (after correct activation) also be installed at an angle, which is often required by the design of modern sports motorcycles.

The favourite for KTM & Honda scooters

The YTX5L-BS is the typical battery for the KTM EXC series (e.g. 250/350/450/500 EXC-F), where it must work reliably despite hard jolts and jumps. It is also a bestseller in the scooter sector, among others for the Vespa ET4 / LX 50-125, Honda Shadow 50/90 or Suzuki Address. It is the perfect balance between low weight and sufficient power.

Characteristics

FAQs on Yuasa YTX5L-BS

What is the difference to the YTX4L-BS?

The footprint is identical (114 x 71 mm), but the height is the decisive factor.

• YTX4L-BS: 86 mm high (3 Ah).
• YTX5L-BS (your battery): 106 mm high (4 Ah). The YTX5L is 2 cm higher. It has more power, but only fits if the battery compartment allows this extra height (seat must still close).

Can I use this battery as a replacement for YB4L-B?

Yes and no.

• YB4L-B (acid): 93 mm high.
• YTX5L-BS (AGM): 106 mm high. The YTX5L is 1.3 cm higher than the classic YB4L-B. If your classic vehicle (e.g. Simson) has room above, the YTX5L is a great technical upgrade (maintenance-free, more starting current). If space is tight, it will not fit.

What does YTZ6V or YTZ7S mean?

In newer sports enduros (KTM, Honda), batteries labelled YTZ6V or YTZ7S are often installed at the factory. These have the same size as the YTX5L-BS (114x71x106 mm), but an even higher performance and capacity (High Performance AGM). The YTX5L-BS is the affordable standard alternative, and the YTZ models are the more expensive premium upgrades.

Do I need to charge the battery?

Yes. As the volume is relatively small, the battery is sensitive to undercharging. After filling (BS version), it should definitely be fully charged with a motorcycle charger (max. 0.4 - 0.6 amp charging current) before installation. This guarantees full starting power for the single-cylinder.