RS125 Bible is an independent workshop record of the Aprilia RS125 two-stroke from 1993 to 2006. It is not affiliated with Aprilia, Piaggio, or any owner, club, or seller. It covers four generations, from the Extrema and GS to the 2006 RSV-style bike, and it leaves a figure blank when the sources do not give one.

Liveries are recorded as model history, and only where a source lists them.

The gap this site is for: there is no single English record that covers every generation with restoration steps, UK law and import, and a parts directory that admits when it does not know a price. Hartrusion is the closest workshop source and it is German-first. rs125.it is the history, in Italian. The forums have the scars, buried in threads.

What “To verify” means

A figure is printed when a named source gives it. Torque, clearances, the PHBH jet stacks, fluids and the chassis checks that Haynes manual 4298 prints are on the specs pages. Those figures are from the workshop manual and should be double-checked on your own bike. The public list of what is still open is the what’s still missing page. A forum number still does not fill a gap. Where the manual and an older note on this site disagree, both stay on the specs overview, including the starter bolts at 10 Nm and at 12 Nm.

“Not published” means the photographed pages of that manual do not give the figure. “To verify” means the site still has no source for it, or the bike in front of you has to settle a question the books leave open.

Still open

• A Loris Capirossi RS125 replica. It is named in passing and not confirmed.
• UK-market model codes and the hardware behind the restricted 15 bhp bikes. The codes in the brief are mostly German homologation data.
• Which years use a Type 122 and which use a Type 123, beyond the research brief. A 1998 bike can be either. Confirm it on the casting.
• Year letters the brief did not list inside 1993–2006, including 1993, 1994 and 2003–2006.
• Pilot-screw turns, float height, needle-clip position, reed-valve clearances, the RS125 fork-oil level, banjo and bleed-nipple torque, head tightening order, balance-shaft tooth marks, gearbox end-float, bearing numbers, sag, Type 122 ignition timing in degrees, and Type 123 unregulated alternator output. Haynes 4298 does not publish them. Oil-pump ranges are on the cooling guide from Hartrusion, and they are not one premix ratio.
• Paint codes and every OEM part number.
• The current eBay Partner Network UK rate and the Demon Tweeks rate. The DVLA first-registration fee was £55 on the GOV.UK page checked 25 October 2026.
• A dated UK asking-price range, in pounds, with the listing it came from.
• Mod gaps: a checked jet stack for a Type 122 with a named pipe, squish, port timings, a timing-wedge angle, a measured exhaust gain on a standard engine, and top-end mileage after tuning.
• Whether ‘RS125’ in a domain needs a trade mark check. The brief marks a UK IPO search as still to do. Aprilia itself is kept out of the site name.

Trade marks

The site is not affiliated with, endorsed by, or connected to Aprilia, Piaggio, Rotax, or any seller named in the directory. Aprilia is a trademark of its owner. It is used here only to identify the motorcycle. It is not used in the logo or the site name.

Corrections

A correction with a source is how the markers come off. Use the form on thecommunity page. Contributors who fix a guide get credited on it. The site ships with no analytics and no advertisements. Affiliate slots render nothing until an ID is set.

Every source in the brief

• Haynes manual 4298 (Aprilia RS50 and RS125 1993-2006) (opens in a new tab) — Haynes
• Aprilia RS125 (opens in a new tab) — Wikipedia
• RS 125 review and buying guide (opens in a new tab) — MCN
• Modellübersicht RS 125 2T (opens in a new tab) — Hartrusion
• Differences between Rotax 122 and 123 (opens in a new tab) — Hartrusion
• Aprilia RS125 parts and engine ID (opens in a new tab) — PJME
• Storia e modelli (opens in a new tab) — rs125.it
• RS 125 replica decal sets by year (opens in a new tab) — Decalmoto
• Aprilia model list (opens in a new tab) — Motorcyclespecs
• Derestriction guide (opens in a new tab) — The RS 125 blog
• Bike categories, ages and licence requirements (opens in a new tab) — GOV.UK
• Importing vehicles: telling HMRC (NOVA) (opens in a new tab) — GOV.UK
• Over-10-year imports exempt from approval (opens in a new tab) — VCA
• RS 125 parts catalogue (PDF) (opens in a new tab) — Aprilia Superstore
• 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
• Fair use: Hobby is non-commercial (opens in a new tab) — Vercel
• RS125 Euro-archive (opens in a new tab) — ApriliaForum
• Aprilia RS125 forum (opens in a new tab) — 125cc Sportsbikes
• Ölpumpe und Getrenntschmierung (opens in a new tab) — Hartrusion
• Zündung einstellen beim Rotax 123 (opens in a new tab) — Hartrusion
• MOT inspection manual: motorcycles (opens in a new tab) — GOV.UK
• MOT manual: wheels, tyres and suspension (opens in a new tab) — GOV.UK
• MOT manual: brakes (opens in a new tab) — GOV.UK
• Registering an imported vehicle (opens in a new tab) — GOV.UK
• Register a used vehicle for the first time (V55/5) (opens in a new tab) — GOV.UK
• New registrations fee (opens in a new tab) — GOV.UK
• Legal obligations of drivers and riders (opens in a new tab) — GOV.UK
• PHBH 28BD settings thread (opens in a new tab) — ApriliaForum
• PHBH 28 air-screw thread (opens in a new tab) — 125cc Sportsbikes
• Carb jetting notes (opens in a new tab) — The RS 125 blog
• Tuning: carburettor (opens in a new tab) — Hartrusion
• Jetting chart, Dell’Orto VHSB 34 (opens in a new tab) — Hartrusion
• Tuning: exhaust systems (opens in a new tab) — Hartrusion
• Tuning: reed valves (opens in a new tab) — Hartrusion
• Tuning: exhaust power valve (opens in a new tab) — Hartrusion
• Exhaust power valve overview (opens in a new tab) — Hartrusion
• Dellorto 34 mm carburettor, 1993 to 2005 (opens in a new tab) — PJME
• 34 mm carburettor inlet manifold (opens in a new tab) — PJME
• Dellorto VHSB 34 LD listing (opens in a new tab) — Pedparts
• Italkit W-Force reed and 34 mm manifold (opens in a new tab) — Moto Part Market
• 34 mm carb notes (opens in a new tab) — The RS 125 blog
• JT 13-tooth sprocket, Rotax 122/123 (opens in a new tab) — Radical Racing
• Racing clutch kit listing, Rotax 122 and 123 (opens in a new tab) — Motorbike Tyres UK