Yuasa YTX9-BS 12V 8.4 Ah
(18 reviews)
The factory-fit reference on many mid-size motorcycles and maxi-scooters: sealed AGM, 135 cranking amps, and the reliability of a century-old maker.
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Characteristics
- Capacity: 12V, 8.4Ah (135 cranking amps)
- Technology: Sealed AGM (VRLA), maintenance free
- Size: 150 x 87 x 105 mm, 3.1 kg
- Polarity: Positive terminal on the left
- The original fitment on 600s and maxi-scooters
Detailed overview: Yuasa YTX9-BS AGM motorcycle battery 135 A
The Yuasa YTX9-BS is a 12 volt starter battery for motorcycles, scooters, ATVs, personal watercraft, and riding mowers. It offers 8.4 amp-hours of capacity and 135 cold cranking amps, in a 150 x 87 x 105 mm case weighing 3.1 kilos, with the positive terminal on the left.
The YTX9-BS designation is not a brand name but an industry-standard reference: it defines dimensions, polarity, and performance all at once. That is what lets you order it without error as soon as you know the bike shipped with one from the factory. Yuasa is precisely the company that created this naming system and supplies a large share of Japanese manufacturers as original equipment.
The technology is sealed AGM, also called VRLA. The electrolyte is held in a glass-fiber separator rather than sitting free: the battery needs no topping up, tolerates vibration well, and will not leak if mounted at a slight angle. It is now the standard on two-wheelers, where space and orientation are tight.
The battery ships dry with its acid bottle separate. Activation happens once, at installation: pour in the electrolyte, let it settle, then charge before first use. That initial charge is not optional, it determines the capacity the battery will reach afterward.
Since a motorcycle is ridden less and recharges its battery poorly, a trickle charger is the logical companion. And to get moving when the breakdown has already happened, a compact jump starter sized for a motorcycle earns its keep in the saddlebag.
EAN: 5050694004483
User manual / Instructions for use
Comparison
On a motorcycle the battery size is set by the manufacturer: the real question is which brand and technology to pick.
| Criterion | Yuasa YTX9-BS | Yuasa YTX7L-BS | Yuasa YTX14-BS | Generic equivalent |
|---|---|---|---|---|
| Capacity | 8.4 Ah | 6 Ah | 12 Ah | Variable |
| Cold cranking | 135 A | 100 A | 200 A | Often overstated |
| Dimensions | 150 x 87 x 105 mm | 115 x 72 x 132 mm | 150 x 87 x 145 mm | By reference |
| Typical use | 600cc sport bikes, maxi-scooters | 125s, small scooters | Cruisers, big-bore bikes | All |
| Observed price | ≈ $73 | ≈ $60 | ≈ $91 | ≈ $30 to $45 |
You do not really choose between these three references: the bike dictates its own, and getting the size wrong means the battery will not fit or the terminals will be on the wrong side. The useful comparison is against generic equivalents, sold twenty to forty dollars less. They often survive the first season, then lose capacity far faster. On a part you replace by pulling a seat and sometimes a tank, the price gap is recovered in the first extra year of service.
Related video
Video: How to Install Dry Electrolyte ATV Battery | Yuasa YTX9-BS - Published on 16/02/2024
Our tester's review: Gilles Caron
Buying a motorcycle battery is rarely fun: you replace it because the old one gave up, usually at the worst possible moment. Better to get the right one the first time, and the Yuasa YTX9-BS is hard to fault. The first argument is industrial, not technical: Yuasa is the original designer of the YTX reference, the same company that fits a large share of Japanese motorcycles from the factory through its US arm, Yuasa Battery Inc. Buying a YTX9-BS means buying exactly what the manufacturer installed, where cheaper compatible copies match the dimensions but rarely the service life. On the technical side, the 135 cold cranking amps matter most, not the amp-hour rating, since that number decides whether the starter spins convincingly on a cold morning. Sealed AGM technology removes the maintenance and handles vibration well. Two honest notes: the battery ships with a separate acid pack to fill at installation, needing a full charge first, and like any lead-acid battery it hates sitting dead, so a trickle charger during winter storage is the best investment you can make alongside it.
Frequently asked questions: Yuasa YTX9-BS AGM motorcycle battery 135 A
The reference is standardized: if your original battery is marked YTX9-BS, replacement is direct, same dimensions and same polarity. If in doubt, check the case size (150 x 87 x 105 mm) and the position of the positive terminal, on the left on this model.
Yes, and it is not optional. The battery ships dry with its acid bottle: after pouring in the electrolyte and letting it settle, an initial charge is required. It directly determines the capacity the battery will reach afterward.
Three to four years in normal use, less if the bike sits through winter without care. A motorcycle is ridden less and its alternator recharges poorly in town riding: a trickle charger connected during storage easily doubles service life.
The dimensions and reference are identical, the quality of the plates and separator is not. Yuasa supplies Japanese manufacturers as original equipment and states a markedly longer service life. On a part you replace by pulling the seat, the price difference is recovered quickly.
Other products in the "Motorcycle batteries" category
Yuasa YTX14-BS 12V 12 Ah
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Two hundred cranking amps: the reference battery that spins big twins, cruisers, and adventure bikes where a YTX9 begins to struggle.
Yuasa YTX7L-BS 12V 6 Ah
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The small battery fitted to half the 125s and scooters on European roads: tall and narrow, 100 cranking amps, and the seriousness of an original-equipment maker.
Published on 02/09/2026