Parts directory
- Categories by generation. Prices are empty on purpose.
- OEM numbers stay empty until they are copied from a catalogue.
- Do not buy 123 parts for a 122.
Directory
Slots, not prices.
OEM numbers and prices are empty on purpose. Enter an OEM number only when it has been copied from the official parts catalogue for that VIN, and enter a price only with the date it was seen. Do not fill either from memory or from a forum.
Measured figures and torque are on the specs pages, from Haynes manual 4298. An OEM number is copied only from the official catalogue diagram for that VIN, then checked against the casting. This directory does not guess one, and it does not print a pound range without a date and a listing.
No parts match those filters. Clear them to see the full directory.
Top end
Rotax 122 and Rotax 123 top ends do not share pistons, barrels or gaskets. Identify the engine before ordering.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| Piston 122 and 123 pistons do not interchange. Order against the casting. Type 122 codes are A and B. Type 123 codes are Red and Green. Service limits are on the engine specs page. OEM numbers are not copied here. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, Pedparts UK, Wemoto, Aprilia UK dealers |
| Piston rings MCN's interval is rings around every 5,500 miles. Haynes 4298 ring gap, new: Type 122 0.05–0.2 mm, Type 123 0.15–0.3 mm. Service limit 0.8 mm on both. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, Pedparts UK, Wemoto |
| Cylinder / barrel Cylinders do not swap. MCN's interval for piston and barrel is around every 10,000 miles. Type 122 bore codes are A, AB and B. Type 123 codes are Red and Green. Limits are on the engine specs page. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, Pedparts UK, eBay UK |
| Reed block and petals Inspect petals for chips. Reed clearances are not published. Mounting bolts are 7 Nm. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, Pedparts UK, Wemoto |
| Cylinder head O-ring Replace rather than reuse. Section and part number are not recorded here. 122 and 123 are not the same part. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Aprilia UK dealers, eBay UK |
| Base gasket Gaskets do not swap between the 122 and the 123. Thickness is not recorded here. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, PJ Motorcycle Engineers, Aprilia UK dealers |
Bottom end and clutch
Crank, main bearings, seals, gearbox and clutch. The 123 clutch is fastened with a nut. The 122 clutch is not.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| Crankshaft The brief says Pedparts lists a Rotax 122 crankshaft. A 123 crank is not the same part, and many 123 parts are discontinued. No OEM number is copied here. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Pedparts UK, PJ Motorcycle Engineers, eBay UK |
| Main bearings Crank bearings are a known bee-tail complaint. Bearing numbers are not recorded here. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, eBay UK, Aprilia UK dealers |
| Crank seals A leaking crank seal leans the engine out. Sizes are not recorded here. Do not guess a seal from the other Rotax. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, PJ Motorcycle Engineers, eBay UK |
| Clutch Type 122: 6 friction and 6 plain plates. Type 123: 6 friction and 5 plain. Spring bolts 7 Nm. The 123 centre nut is 80 Nm. The brief says the 122 has no centre nut. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Aprilia UK dealers, eBay UK |
RAVE powervalve
Blade, blanking plate, solenoid, cable and the control unit. Restricted bikes may have a blanking plate instead of the blade.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| RAVE blade The derestriction steps in the brief say the blade goes taper down, flat side up. Confirm that orientation in the manual for your year. To verify the part number. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, eBay UK, Aprilia UK dealers |
| Powervalve blanking plate Fitted in place of the RAVE blade on many restricted bikes. The brief does not list a part number. The Extrema/GS had no factory-restricted version, per Hartrusion. | Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK |
| RAVE solenoid The brief includes a 12 V solenoid test. A seized solenoid is a known bee-tail fault. Connector pinout is not recorded here. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK, Aprilia UK dealers, Wemoto |
| RAVE cable Free play is 0.5 mm. The adjustment steps are in the manual and are not reprinted here. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, eBay UK |
Carburettor
The research brief puts a VHSB 34 on the Rotax 123 and a PHBH 28 on the Rotax 122. Haynes 4298 lists a PHBH28BD for both power columns.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| Dell'Orto VHSB 34 The 34 mm carburettor on the Rotax 123. PJME is named in the brief as a supplier of 34 mm carburettors. | Extrema / GS, Round-light RS 125 | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, eBay UK |
| Dell'Orto PHBH 28 The 28 mm carburettor on the Rotax 122. Not every round-light bike has one: UK and much of Europe kept the 123 and the 34 mm carb into about 1997–98. | Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, eBay UK, Pedparts UK |
| Jets, needle and slide Haynes 4298, for a PHBH28BD only: main jet 115 at 11 kW and 120 at 20 kW, pilot 62, starter 70, needle BN 264 restricted and BN 266 unrestricted. Do not put those jets in a VHSB 34. A blog also mentions a main moving up from 115. Pilot-screw turns are not published. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, Pedparts UK, eBay UK |
Ignition and electrics
SEM on the 123 and a Nippondenso CDI on the 122.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| SEM stator 123 ignition. The brief says SEM stators are hard to find. Not used on the 122. | Extrema / GS, Round-light RS 125 | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK |
| Nippondenso CDI 122 ignition. The brief describes an environmental retard around 5–6,000 rpm. How the bridge differs by unit is To verify. Do not follow a pinout that is not in the manual for that CDI. | Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK, Aprilia UK dealers |
| Immobiliser / alarm Owners report trouble with the factory immobiliser on the RSV-style bikes. No repair procedure is copied here. | RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Aprilia UK dealers |
| Mechanical tacho drive shaft The brief says this shaft is fragile and no longer available. | Extrema / GS | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK |
| Rear-wheel speed sensor The RSV-style digital dash takes road speed from a rear-wheel sensor rather than a gearbox drive. | RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Aprilia UK dealers, eBay UK |
Cooling and oil
Water pump, thermostat, oil pump and feed lines. Warm the engine to 60°C before hard riding (MCN, via the brief).
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| Water pump Seal and impeller part numbers are not recorded here. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Aprilia UK dealers, eBay UK |
| Thermostat Begins to open at 70–75°C. Maximum lift 3.3 mm at 90°C. The 60°C warm-up figure is a riding practice from MCN, not the thermostat rating. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Aprilia UK dealers |
| Coolant Half distilled water, half ethylene glycol antifreeze for aluminium engines. About 0.9 litres. A premix ratio for the two-stroke oil is not published. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Sportsbikeshop |
| Oil pump and feed lines Pumped oil feed. Stroke, premix ratio and a grade code are not published. MCN says a premium two-stroke oil. Gearbox oil is separate: SAE 75W-90, about 850 cc. Do not ride with an empty oil tank. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Aprilia UK dealers, eBay UK, Wemoto |
Exhaust
Expansion chamber, and a catalyst in the chamber from 2003. Corrosion is a repeated owner complaint.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| Expansion chamber From 2003 the SF has a catalyst in the chamber, and the 2006 RSV-style bike keeps one. A non-catalyst pipe is part of the derestriction path in the brief. Brand names and part numbers are not recorded. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | PJ Motorcycle Engineers, eBay UK |
| Secondary air system Added on the SF for 2004, and present on the 2006 bike as the SLS. Individual parts are To verify in the catalogue. | Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Aprilia UK dealers, Aprilia parts catalogues |
Brakes
The research brief says axial front calipers to 2005 and radial from 2006. Haynes 4298 describes four opposed pistons at the front and two at the rear, and lists DOT 5.1.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| Front brake pads, axial caliper Through the bee-tail (to 2005), on the research brief's axial-caliper record. Friction material minimum 1.5 mm. Compound and the part number are not published. | Extrema / GS, Round-light RS 125, Bee-tail | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Sportsbikeshop, eBay UK |
| Front brake pads, radial caliper Radial front pads for the 2006 RSV-style bike. Compound is not recorded. To verify before ordering. | RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Sportsbikeshop, Aprilia UK dealers |
| Brake hoses Braided lines are standard on the RSV-style bike. Hose type on earlier generations is To verify. Banjo torque is not published in Haynes 4298. | RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Sportsbikeshop, Wemoto |
| Brake fluid Haynes 4298 lists DOT 5.1, and lists it as compatible with DOT 4. Read the reservoir cap as well. Do not mix grades. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Sportsbikeshop |
Suspension and bearings
USD fork seals, shock, headstock bearings and wheel bearings. Fork oil quantity is published. Sag and bearing numbers are not.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| USD fork seals and oil The RSV-style bike has a new fork. Seal size is To verify. Fork oil is SAE 10W to 20W, 430 cc each leg. The RS125 oil level is not published. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Sportsbikeshop |
| Rear shock Linkage lengths and spring rates are not recorded. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK, Aprilia UK dealers |
| Headstock bearings Bearing numbers are not recorded. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, eBay UK |
| Wheel bearings Sizes are not recorded. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Wemoto, Sportsbikeshop |
| Speedo drive The brief says speedo drives wear out on the bee-tail. The RSV-style dash uses a rear-wheel sensor instead. | Extrema / GS, Round-light RS 125, Bee-tail | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK, Wemoto |
Bodywork and decals
Fairing shape, headlight and decal kits differ by generation. A replica kit does not change the mechanical bike.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| Headlight unit Rectangular on the Extrema/GS, round with a lip on the 1995/96–1998 bike, then the bee-tail shape, then twin headlights on the 2006 RSV-style bike. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | eBay UK, Aprilia UK dealers |
| Fairing brackets and fasteners Brackets differ by generation. Do not force a bracket from another bodywork onto this frame. Sizes are not recorded. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Aprilia UK dealers, eBay UK, Aprilia parts catalogues |
Two-stroke spark plugs
Haynes 4298 lists an NGK BR10EG, gap 0.5–0.7 mm. A derestriction blog also names a BR8EG, which that manual extract does not list.
| Part | Fits | OEM number | Last price | Suppliers |
|---|---|---|---|---|
| NGK BR8EG Named in a derestriction blog as the plug you are leaving. Haynes 4298 does not list it. The manual's plug is the BR10EG. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Sportsbikeshop |
| NGK BR10EG Haynes 4298 lists this plug for the RS125. Electrode gap 0.5–0.7 mm. Torque 20 Nm. A blog also names it as the colder plug after derestriction. | Extrema / GS, Round-light RS 125, Bee-tail, RSV-style | Not recorded To verify | Not recorded No date, because no price has been entered. | Sportsbikeshop |
Suppliers named in the brief
These are ordinary links to the sites the brief named. Tracked affiliate links are a separate slot and stay invisible until an ID is set in the environment. See the README.
| Supplier | Useful for | Affiliate scheme |
|---|---|---|
| Pedparts UK (opens in a new tab) | Dedicated RS/RX/MX 125 section; the brief says the range lists a Rotax 122 crankshaft. | To check |
| Wemoto (opens in a new tab) | UK online pattern and OEM-style parts, with an Aprilia range. | None found |
| PJ Motorcycle Engineers (opens in a new tab) | UK RS125 specialist: pistons, barrels, big-bore kits, 34 mm carburettors. Recommended by MCN. | To check |
| Aprilia UK dealers (opens in a new tab) | Genuine parts through authorised dealers. | No |
| Aprilia parts catalogues (opens in a new tab) | Exploded diagrams. OEM numbers are copied only for the bike in front of you, not from memory. | No (reference) |
| Decalmoto (opens in a new tab) | Replica decal kits. The brief records a rough price of €95–€140, which is not a GBP price. | To check |
| Sportsbikeshop (opens in a new tab) | Consumables, tools and riding kit. | Yes: 8% new customers / 2% returning, 10-day tracking. Programme not connected on this site. |
| eBay UK (opens in a new tab) | Used and NOS parts, and breakers. | Yes (eBay Partner Network). The 2019 UK rate card in the brief says 2.5% for vehicle parts. Rate to verify. Programme not connected on this site. |
Rates the brief wrote down
None of these programmes is connected. The rates are here so they are not forgotten, and so the doubtful ones stay marked.
- eBay Partner Network: vehicle parts and accessories at 2.5% on the 2019 UK rate card. To verify the current rate.
- Amazon Associates UK: automotive 5%, other categories 3%, as recorded in the brief.
- Sportsbikeshop: 8% for new customers, 2% for returning customers, 10-day tracking.
- Demon Tweeks via Awin: motorcycle about 3%, 30-day cookie, from a third-party summary. To verify.
A parts-catalogue PDF is linked in the sources. Numbers are not copied into the tables above until a person has checked the diagram for a specific VIN.
Sources
- Haynes manual 4298 (Aprilia RS50 and RS125 1993-2006) (opens in a new tab) — Haynes
- Aprilia RS125 parts and engine ID (opens in a new tab) — PJME
- RS 125 parts catalogue (PDF) (opens in a new tab) — Aprilia Superstore
- RS 125 replica decal sets by year (opens in a new tab) — Decalmoto
- Affiliate programme (opens in a new tab) — Sportsbikeshop
- Associates commission rates (opens in a new tab) — Amazon UK
- EPN UK rate card (2019) (opens in a new tab) — eBay
- RS 125 review and buying guide (opens in a new tab) — MCN
Research brief dated 24 October 2026. Where this page says “the brief”, that is the sourced master plan behind the first edition.