Yuasa YTX9-BS 12V 8.4 Ah
(15 reviews)
Europe's most widely fitted reference on mid-capacity motorcycles and maxi-scooters: sealed AGM, 135 cranking amps, and the reliability of a century-old maker.
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Characteristics
- Capacity: 12 V, 8.4 Ah (135 cranking amps)
- Technology: Sealed AGM (VRLA), maintenance free
- Format: 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, quad bikes, jet skis and ride-on 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 trade 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 the bike was fitted with one from new. Yuasa is precisely the maker that created this nomenclature and supplies a large share of Japanese manufacturers as original equipment.
The technology is sealed AGM, also known as VRLA. The electrolyte is held in a glass-fibre separator rather than floating free: the battery needs no topping up, tolerates vibration well and will not leak if slightly tilted. It is now the standard on two-wheelers, where space and orientation are constrained.
The battery ships dry with its separate acid bottle. Activation happens once, at fitting: 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 subsequently reach. In some markets, the United Kingdom included, the same battery is also sold factory-activated as YTX9 (WC).
Since a two-wheeler is ridden little and recharges its battery poorly, a trickle charger is the logical companion: see the Einhell CE-BC 4 M or the Bosch C30, both 6 and 12 volt capable and suited to small capacities. And to get going when the breakdown has already happened, the Noco GB20 is the right size of jump starter for a motorcycle.
EAN: 5050694004483
User manual / Instructions for use
Comparison
On a motorcycle the battery reference is imposed by the manufacturer: the real question is which brand and which technology you 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 | 600 cc road bikes, maxi-scooters | 125s, small scooters | Cruisers, big capacity | All |
| Observed price | ≈ 73 € | ≈ 57 € | ≈ 67 € | ≈ 30 to 40 € |
You do not choose between these three references: the bike imposes its own, and getting the format wrong means the battery will not fit or the terminals will be on the wrong side. The useful comparison is with generic equivalents, sold fifteen to twenty euros less. They often survive the first season, then lose capacity far faster. On an item you replace by removing a seat and sometimes a tank, the price gap is recovered on the first extra year gained.
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 a pleasure: you replace it because the previous one gave up, usually at the worst possible moment. Better to get the right one first time, and in this segment Yuasa's YTX9-BS is hard to fault. The first argument is not technical but industrial: Yuasa is the original maker of the YTX reference, the supplier fitting a good share of Japanese motorcycles from the factory. Buying a YTX9-BS from Yuasa means buying exactly what the manufacturer installed, where compatible copies sold twenty euros cheaper share the dimensions but rarely the service life. Technically, the 135 cold cranking amps are what really counts. It is that figure, not the amp-hour capacity, which decides whether the starter spins convincingly on a three-degree morning. Sealed AGM technology removes maintenance, copes well with the vibration of a single or a twin, and allows a slightly tilted installation with no risk of leakage. Two honest remarks. The YTX9-BS ships with its acid pack to be poured in at fitting: the operation is simple but calls for gloves, goggles and a little method, and once activated the battery must be charged before first use. Second, like all lead-acid, it hates being left flat: if your bike hibernates, a trickle charger is the best investment you can make alongside it, otherwise you will be buying another one in spring. Note that in the United Kingdom the battery is often supplied factory-activated under the YTX9 (WC) designation, electrically identical.
Frequently asked questions: Yuasa YTX9-BS AGM motorcycle battery 135 A
The reference is standardised: 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 subsequently reach.
Three to four years in normal use, less if the bike sits through winter unattended. A two-wheeler is ridden little and its alternator recharges poorly in town: a trickle charger connected during hibernation 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 quotes markedly longer life. On a part you replace by removing the seat, the price difference is recovered quickly.
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Two hundred cranking amps: the reference that spins big twins, cruisers and adventure bikes where a YTX9 starts to struggle.
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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 26/07/2026