Clutch sprocket -DRT Vespa type 7 springs (Rally200, PX200, T5 125cc)- for primary gear DRT 62 tooth (straight) – 25 tooth

How to install?

The 62 tooth DRT primary gear can only be combined with the corresponding DRT clutch sprockets with 23, 24 or 25 teeth, which are manufactured to the 62 tooth gear. For installation, the motor must be opened completely and the primary riveted again. A primary repair kit is necessary for this purpose. Always use the primary repair kit of the 200cc models, even if the base engine is a PX80 or PX125/150 engine. The 200cc version has double springs which have more resistance to the high torque than the single springs of the small engines. The dimensions of the repair kit are otherwise the same.

The sprockets are available for the 7-spring version of the old engines and for the modern 8 or 10 spring version of the Cosa2 models. Therefore the DRT primary parts cannot be combined with the small 6-spring clutch type of the 80-150cc models. This is also not recommended as this type of clutch would be overstrained with the high torque.

Why install ?

Many engines are too short reduction ratios after a cubic capacity upgrade or generally due to a power increase. The engine overspeeds in fourth gear and cannot convert its power into top speed. It is also annoying to have to shift gears quickly to stay in the power band.

• PX125

The gearbox of the 125cc and 150cc PX models is almost identical to the PX200.

Some of the first and fourth gears are one tooth shorter. The primary side is the short 68 tooth gear as on the PX80. Because of the much longer secondary gear the change of the clutch pinion to 22 teeth (original available) or 23 teeth (special pinion from DRT) is enough to be sufficiently long also for 177/187cc cylinders.
Alternatively the primary of the 200cc models can be used. The overall reduction ratio is then almost the same as the PX200 (fourth gear is one tooth shorter). For high rpm engines we recommend the use of the DRT Spitfire Road gear reducer. The gear step between 3->4 is much shorter, which improves the gear connection in the upper speed range. For a sufficiently long overall reduction ratio, the ultralong primary available from DRT is also used here. This way the total reduction can be chosen long enough to reach a high top speed despite the shortened secondary gear.

• PX200

The transmission of the 200cc models is the longest of the PX series and corresponds in the gradation to the Rally180/200 and Cosa200 models. It is sufficiently long, but some pointed engines can fall into an unsightly speed hole when changing gears 3->4. The fourth gear can be shortened by the gearwheel of the 125cc models which has 36 teeth instead of 35 teeth. This corresponds to a change of 4km/h at 8000 rpm. For a sporty, closely stepped gearbox we recommend the use of the DRT Spitfire Road gear reducer. The gear step between 3->4 is much shorter and the gear connection in the upper speed range is much better. For a sufficiently long overall reduction ratio, the DRT Spitfire Road primary is also used here. This means that despite a shortened secondary gear the total reduction can be chosen long enough to reach a high top speed. In addition, the other gear ratios can also be changed by using the gear wheels available from DRT. Whoever owns a Polini 210cc/221cc can also benefit from the DRT primary parts.

The speed range of the Polini cylinders is almost the same as the original engine. So if you want to drive much faster than the original with the much higher power and the full torque of these cylinders, you should choose at least a 24 tooth clutch pinion for the original helical primary gear (65 teeth) or, if the engine has to open for another crankshaft anyway, you should use the straight-toothed DRT pinion with 62 teeth. Due to the straight toothing, there are no more lateral forces acting on the bearings and the auxiliary shaft seat. For high torque engines this is always a good choice to protect the material. Three different clutch pinions (23/24/25) are available which can be combined with the 62-tooth primary gear. In this way, even a torque steamer can be moved sufficiently fast without overspeeding.

FITS :

• Vespa (Piaggio) Vespa 180 Rally (VSD1T)
• Vespa (Piaggio) Vespa 200 Rally (VSE1T, Femsa)
• Vespa (Piaggio) Vespa 200 Rally (VSE1T, Ducati)
• Vespa (Piaggio) P 200 E (VSX1T, -1980)
• Vespa (Piaggio) PX 200 E FL (VSX1T, 1984-1997)
• Vespa (Piaggio) PX 200 E (VSX1T, 1981-1983)
• Vespa (Piaggio) PX 200 E FL (ZAPM18, 1998-)