Rotax 123 engine

Presentation

Le Rotax 123 is a 125cc two-stroke engine that was fitted to the Aprilia RS 125 between 1993 and 1997, and on the models AF1 since 1988. It represents an older generation than the Rotax 122, with a more compact design but more difficult to maintain today.

Technical specifications

• Displacement : 124,82 cm³

• Bore 54mm

• Course 54,5mm

• Compression ratio : 12,5 ± 0,5:1

• Primary transmission ratio : 20/64 (slightly faster than the 122 at equal revs)

• Ignition : Integrated SEM (Sweden), with internal stator and coil

• Coils : SEM TM14-04 101 888 00

Technical features

• Integrated ignition : The SEM system does not include an external control unit (no separate CDI). Everything is contained within the stator and coil. Not compatible with the Rotax 122 system.

• Ignition advance : More important at low revs than on the Rotax 122, which provides a theoretical power gain.

• Cylinder :

  • Main reference: 223616 (220D)

  • versions without reinforcement channel (Gilardoni 1 or 2, not compatible with 122)

  • versions with reinforcement channel (logo Aprilia), interchangeable with care.

  • Narrower cylinder drive: 82 mm between studs on the exhaust side.

• Engine speed measurement : Mechanical, via a driven shaft par plastic gears (fragile and difficult to find).

Starter & kickstarter

• Electric starter : Less reliable than the Rotax 122. The freewheel system is particularly sensitive to wear, dirt and incorrect assembly.

• Frequent problems : Premature wear of the flywheel pinion, rare and expensive parts.

• Conversion to kickstarter : Practically impossible today. The complex assembly and rare or even impossible-to-find parts make this operation unrealistic.

Carburettor

The Rotax 123 is usually paired with a carburetor Dell'Orto VHSB 34 34 mm in diameter. It offers better performance at high revs but requires more careful maintenance.

Chassis compatibility

The Rotax 123 is designed for executives of RS 125 produced before 1997. The attachment point under the swingarm axle is positioned differently. Installation in a later frame requires significant adaptations.

Compatible parts for your ROTAX 125 engine

Find on 50 Factory all the ideal parts for the repair and maintenance of your two wheels. You can find par example all types of fairings (rear bib, front mudguard, headlight fairingâ € ¦), parts Power (spark plug , full ignition, Battery, Speedometerâ € ¦), parts engine (carburettor, cylinder , gearbox, exhaustâ € ¦), parts chassis parts (handlebar, tires, brake pads, mirrorâ € ¦) or even amenities (Headphones, gloves, jacket) And some cleaning products (oil, grease, lubricantâ € ¦).

Most of the engine parts that you will find for your motorbike 125cc having a typical engine ROTAX 123 are used parts from damaged motorcycles. These parts are removed and then cleaned par professional mechanics to offer you items in very good condition and offering similar performance to the original! Usually these are original manufacturer parts. If you are looking for a precise part, we advise you to regularly look on our site, car stocks are replenished very often.

Complete engines ROTAX 123 125cm3 second-hand that we offer for sale are completely disassembled, checked and then restored. They are guaranteed for 3 months and you will find all the technical characteristics and other photos directly on the engine product sheet.

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