Honda Super Cub C125, Trail125 and Dax Key Replacement

Quick answerThese three 125s share an engine layout but not a key. The Super Cub C125 is keyless, with a Honda Smart Key fob that has to be registered to the bike. The Trail125 and the Dax 125 use a plain cut key with no chip. Know which one you have before you call, because the replacement jobs are completely different.

Honda Super Cub C125, Trail125 and Dax key quick facts

Honda's 2019 and 2024 Super Cub C125 manuals describe the Honda Smart Key system, which unlocks the ignition switch, the steering lock and the seat with the fob in range.
The Super Cub's fob comes with an ID tag, and its battery is a CR2032 coin cell.
Honda's 2021 and 2025 Trail125 manuals show two ignition keys and a bar-coded key tag, with no immobilizer section.
The 2025 Dax 125 manual shows an ignition key and a key number plate, with no immobilizer section.
On all three the fuel fill cap is under the seat and has no lock of its own.

Honda Super Cub C125, Trail125 and Dax key types by year

Years	Models	Key type	Chip	Notes
2019-present	Super Cub C125 ABS	Honda Smart Key fob	yes	Keyless. The fob is authenticated by radio before the ignition switch will turn. Anti-theft alarm and answer back functions on the fob.
2021-present	Trail125 ABS	mechanical cut key	no	Two keys and a key tag with bar code. Ignition with steering lock, and a seat lock.
2025	Dax 125	mechanical cut key	no	Key number plate supplied. Ignition with steering lock, and a seat lock.

Super Cub C125: no keyhole at all

Honda's manual describes the system as two-way authentication between the motorcycle and the Smart Key. With the fob in range you push the ignition switch, the bike checks that it is a registered fob, a buzzer sounds and the Smart Key indicator comes on, and only then will the switch turn. If someone without the fob tries, the switch just spins freely. The seat opens from a button that works when the fob is in range and the ignition is off or locked, and the fuel cap is under that seat.

The fob has three buttons: an on and off button for the Smart Key function itself, an alarm button for the anti-theft alarm, and an answer back button that makes the bike signal so you can find it. Honda's manual says not to leave the fob in any compartment on the bike.

Each bike is delivered with an ID tag carrying an ID number. The manual's troubleshooting pages tell owners with a broken fob to bring the ID tag to the dealer, and they include an emergency way of unlocking the ignition that relies on that ID number. Honda's advice is to carry the ID tag, but separately from the Smart Key so you cannot lose both at once, and to keep a copy of the ID number somewhere safe that is not on the motorcycle. Without a working fob and without the ID number, your options narrow quickly.

Need a key for your Super Cub C125?

Call or text with the year and where the bike is parked.

Call (619) 775-1858 Text your year, make and model

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Trail125 and Dax 125: ordinary keys

The Trail125 and the Dax are much simpler. Each has a keyed ignition switch that also locks the steering, and one more lock at the seat.

Trail125 seat: key clockwise in the seat lock; the fuel cap and helmet holder are under the seat
Trail125 tool box: opened with the supplied hex wrench, not the key; it holds the tool kit, document bag and helmet set wire
Dax seat: key clockwise in the seat lock and the seat opens; the fuel cap, helmet holder and tool kit are underneath, and the document bag is on the underside of the seat
Both seats lock again when pushed down at the rear, so do not leave your only key underneath

What to watch on each

Super Cub: a weak fob battery is the first thing to rule out when the bike stops responding, and a CR2032 is easy to replace. Honda's manual also notes that the seat may not open if the bike's own battery is too low to start the engine, which surprises owners who only wanted to get to the fuel cap.

Trail125: the seat lock matters more than on most bikes, because the fuel cap is under the seat. On a bike that gets ridden on dirt, keep that lock clean and working, since a seat lock that will not turn also stops you from refueling.

Dax: the seat lock guards the fuel cap, the helmet holder, the tool kit and the document bag, so one lost key shuts you out of all of them. If you bought yours used with a single key and no key number plate, have a spare cut now.

Losing the key or the fob

Trail125 or Dax: we check photo ID and your registration or title, cut a key to the bike on site, and test it at the ignition, the steering lock position and the seat. No programming is needed.

Super Cub: a lost fob is an electronic job. A replacement Smart Key has to be registered to the bike, and Honda's manuals point owners to the dealer with the ID tag. Call us with the model year and tell us whether you still have a second fob and the ID tag. We will say plainly whether it is something we can do where the bike is or whether the dealer is the better route. If you have one working fob today, get the second one sorted before you need it.

Where to find the key code

Trail125: on the bar-coded key tag that comes with the two keys. Dax 125: on the key number plate. Super Cub C125: there is no cut-key number to speak of; what matters is the ID number on the ID tag supplied with the Smart Key, which Honda's manual refers to for emergency unlocking and dealer service.

What to have ready

Have this ready when you call or text

Year, make and model of the bike
Where the bike is parked
Whether you have any working key, a broken key or a key code
Photo ID and registration or title (we verify ownership before making a key)

Honda Super Cub C125, Trail125 and Dax key FAQ

Is the Honda Super Cub C125 keyless?

Yes. Honda's manuals describe the Honda Smart Key system: you keep the fob on you and operate the ignition switch without inserting a key.

Does the Trail125 use the same Smart Key as the Super Cub?

No. Honda's Trail125 manuals show two ordinary ignition keys and a key tag. It is a plain cut key with nothing to register.

My Super Cub will not respond to the fob. Is the fob dead?

Check that the Smart Key function on the fob is switched on, then try a new CR2032 battery. If the bike's own battery is low, that can also stop things working. If none of that helps, call with the model year.

How do I refuel a Trail125 or Dax if I lost the key?

You cannot until the seat is open, because the fuel cap is under it. A replacement key cut to the bike opens the seat as well as running the ignition.

What is the ID tag that came with my Super Cub?

It carries the ID number for your Smart Key system. Honda's manual refers to it for emergency unlocking and tells owners to bring it to the dealer when a fob is broken. The manual says to carry the tag separately from the Smart Key and to keep a copy of the number in a safe place that is not on the bike.

The immobilizer system on this bike

Honda Smart Key: Fobs, ID Tags and What to Do If You Lose OneHonda Smart Key is a keyless system: the bike checks for a registered fob nearby and then lets you unlock the steering, switch on and start, with no key in a slot.

More Honda models

Services for this bike

Motorcycle Key Fob Battery Replacement by MakeMost motorcycle key fobs run on a single 3 volt coin cell.
Keyless Motorcycle Not Detecting the Key: Causes and BackupsOwner's manuals give a short list of reasons a keyless bike fails to detect its fob: a weak fob battery, the fob carried against a phone, laptop or metal object, strong radio interference nearby, the fob switched off or out of range, and a low battery on the bike itself.
Mini Motorcycle and Moped Keys: Grom, Monkey, RuckusA lost key on a mini motorcycle is usually one of the simpler key jobs.
Signs Your Motorcycle Ignition Switch Is FailingA motorcycle ignition switch is two parts in one housing: a lock cylinder that reads the key and an electrical switch that powers the bike.

Where we come to you

Sources

Page last updated November 14, 2026.