Aprilia RS 50, RS 125 and RS4 Key Replacement

Quick answerAprilia's small sport bikes keep things simple. The owner's books for the RS 50, RS 125, RS4 50 and RS4 125 all describe two ordinary keys, one of them a spare, and none of them has an immobilizer section. The one key works the ignition and steering lock, the fuel tank lock and the saddle lock, so a lost key is replaced by cutting a new one to the bike.

Aprilia RS 50, RS 125 and RS4 key quick facts

Aprilia's use and maintenance books for the RS 50 and RS 125 say the key operates the ignition switch and steering lock, the saddle lock and the fuel tank lock.
The RS4 50 and RS4 125 owner's manuals say the same in newer wording: ignition switch and steering lock, fuel tank cap lock and saddle lock.
All four books state that two keys are supplied with the vehicle, one of them a spare.
On the RS4 125 the fuel cap sits under a lock protection cover and can only be refitted with the key inserted.
The RS 125 book warns you to check that the key has not been left in the glove and tool kit compartment before locking the saddle.
None of these manuals describes an immobilizer, a coded key or a key programming procedure.

Aprilia RS 50, RS 125 and RS4 key types by year

Years	Models	Key type	Chip	Notes
2003 edition manuals	RS 50, RS 50 Tuono, RS 125, RS 125 Tuono	mechanical cut key	no	Two keys supplied. Ignition and steering lock, saddle lock and fuel tank lock on one key.
2010s	RS4 50	mechanical cut key	no	Two keys supplied. The key turns clockwise to open the fuel cap and to release the rider saddle.
2012 manual	RS4 125	mechanical cut key	no	Two keys supplied. Fuel cap lock sits under a protective cover; the cap closes only with the key in it.

Small Aprilias and the chip key question

Aprilia's larger road bikes moved to transponder keys with a user code, and that reputation follows the brand down to its smallest models. It does not apply here. The RS 50 and RS 125 two-strokes and the RS4 four-strokes that replaced them have an ignition switch on the upper steering plate with three positions, ON, OFF and LOCK, and a key that is nothing more than cut metal. The manuals describe the positions and when the key can be taken out, and that is the whole key chapter.

If a seller or a parts counter tells you that your RS needs a code card or a dash procedure for a new key, they are thinking of a different Aprilia.

Need a key for your RS 50?

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

Call (805) 429-8452 Text your year, make and model

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Ignition, tank and saddle

Everything is on one key, and the bike was delivered with only two. A used bike may come with only one of them.

Ignition switch and steering lock: set the key to OFF, then push it in and turn it toward LOCK while easing the handlebar round until it catches
Fuel tank lock: insert the key, turn it clockwise and lift the cap or flap
Saddle lock on the RS 50 and RS 125: the key releases the rider saddle, with a small glove and tool kit compartment beneath
Saddle lock on the RS4: the key releases the rider saddle, and the passenger saddle comes off afterward with a lever, no second lock involved

Mismatched locks and bent keys

Small sport bikes get dropped and repaired. An ignition switch swapped after a crash will no longer match the tank cap and saddle, and a key can be bent in a fall.

A mismatched set can be brought back to one key by setting the odd lock to match the others. A bent key should be replaced, not straightened and trusted, because a blade that snaps inside the ignition turns a small job into a bigger one.

Replacing a lost RS or RS4 key

Since no electronics are involved, the work is all at the locks. We check photo ID and your registration or title, make a key from the bike's locks, and try it in the ignition, the steering lock position, the tank cap and the saddle lock before handing it over.

Some small-displacement bikes are sold on a bill of sale without a current registration. If that is your situation, tell us what paperwork you do have before we set out, because proof of ownership comes first on every job.

Where to find the key code

The RS and RS4 owner's books list the keys supplied but do not describe a key code tag. Check the original sales folder in case the selling dealer noted a number. In most cases the key is made directly from the locks on the bike.

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)

Aprilia RS 50, RS 125 and RS4 key FAQ

Does an Aprilia RS 125 have an immobilizer?

The RS 125 use and maintenance book describes two plain keys and has no immobilizer section. A correctly cut key starts the bike.

Is the RS4 50 key programmed to the bike like on an RS 660?

No. The RS4 50 owner's manual describes a key that works the ignition and steering lock, the fuel tank cap lock and the saddle lock, with no coded key or user code. The RS 660 is a different system.

My RS 50 has one key for the ignition and another for the tank. Can that be fixed?

Yes. From the factory one key did everything, so a second key means a lock was changed at some point. We can usually match the locks to a single key during one visit.

I locked my only key under the RS 125 saddle. What now?

Aprilia's manual warns about exactly that. We can open the saddle lock without damage and cut you a spare while we are there.

More Aprilia models

Services for this bike

Locked Your Keys Under the Motorcycle or Scooter Seat?Keys get locked under the seat because most seats latch shut with a push and need no key to close.
Mini Motorcycle and Moped Keys: Grom, Monkey, RuckusA lost key on a mini motorcycle is usually one of the simpler key jobs.
Worn or Bent Motorcycle Key: Signs, Risks and the Right FixA worn motorcycle key shows up as a key that needs wiggling, works in one lock but not another, or works worse than the spare.
One Key for All Your Motorcycle Locks: Keying AlikeA motorcycle that needs different keys for the ignition, fuel cap and seat has almost always had a lock replaced.

Where we come to you

Sources

Page last updated November 14, 2026.