PowerStar UT4B (YT4B-BS) 12V 4Ah Motorcycle Battery — Yamaha TTR50/TTR90 Fit, Sealed AGM

PowerStar UT4B (YT4B-BS) is a compact, sealed 12V 4Ah AGM battery built as a drop-in replacement for small motorcycles and ATVs like the Yamaha TTR50, TTR90 and SR400.

This PowerStar battery delivers the starting and accessory power riders need in a tiny, maintenance-free package. Its absorbed glass mat (AGM) design keeps electrolyte contained so there’s no filling or acid handling; the battery ships charged and ready to install. With standard terminal layout and common OEM dimensions, it replaces many PTX/GT/CT series small-block batteries so you can get reliable cold starts and steady accessory performance without battery upkeep.

Will this battery fit my Yamaha TTR50 or TTR90?

Yes — the UT4B / YT4B-BS sizing and terminal placement match the compact battery compartments used on smaller Yamaha off-road and commuter bikes. Before ordering, confirm your current battery group size and terminal orientation to ensure a drop-in swap without modification.

• Dimensions: 4.45" L x 1.5" W x 3.35" H (inches)
• Voltage & capacity: 12V, 4Ah
• Cold Cranking Amps (CCA): 30
• Common cross-references: PTX4B-BS, GT4B-5, CYT4B-BS, M62T4B, WP4B-BS

How is the PowerStar UT4B maintained and charged?

The UT4B is sealed AGM and maintenance-free, so you never need to add water or handle acid. Charging is straightforward with any charger that supports 12V AGM or sealed lead-acid batteries; use a smart charger to preserve service life between rides.

• Sealed, leak-free AGM construction—no acid topping up
• Ships pre-charged for immediate installation
• Use a 12V AGM-compatible smart charger for long-term storage
• Minimal self-discharge compared to flooded lead-acid cells

What performance can I expect for starting and accessories?

Despite its small size, this battery supplies enough burst current for kick or electric start systems on lightweight bikes and powers lights, horns and small accessories reliably. Its 30 CCA rating is matched to the modest starting needs of small-displacement engines while the AGM format provides stable voltage under load.

• 30 CCA for reliable cranking on small engines
• Steady accessory power for lights and electronics
• Low internal resistance helps deliver quick bursts of current
• Suitable for motorcycles, ATVs, scooters and personal watercraft

Who is this for? Riders, mechanics and fleet managers who maintain small-displacement motorcycles, scooters or compact ATVs and need a dependable, maintenance-free replacement will appreciate the PowerStar UT4B. It’s especially convenient for owners of Yamaha TTR50/TTR90 series and SR400 who want a direct-fit, sealed AGM battery that arrives ready to install without acid handling or routine maintenance. If you need a lightweight, compact battery that matches common OEM cross-reference numbers and performs reliably in everyday use, this model is a practical, cost-effective choice.