Some MINARELLI Motorcycle Engine Service Manuals PDF above the page - AM6, MA50, V1.
Minarelli motors without a catalyst are installed on most scooters Aprilia (excluding Habana, SR2000LC), Beta, Benelli (until March 2003), MBK, Yamaha, Malaguti (excluding Crosser), ItalJet Dragster and KTM.
There are five different versions of these engines - the horizontal cylinder engine exists in both liquid and air-cooled versions, both of which have both long and short crankcases. The vertical cylinder motor only exists in the air-cooled version with a long crankcase.
Minarelli uses the following markings for five engine models:
Type MA - horizontal cylinder, liquid cooled, long crankcase motor (e.g. SR Netscaper / Stealth .., Nitro, Aerox, F15, F12 LC)
Type MY - motor with a horizontal cylinder, air-cooled, with a long crankcase (for example SR WWW, Neo’s, Ovetto, Rally AC, F12 AC)
Type CA - Horizontal Cylinder, Liquid Cooled, Short Case (e.g. Sonic LC)
Type CY (aka 3KJ) - a motor with a horizontal cylinder, air cooling, with a short crankcase (for example, Sonic AC F10, Yamaha Jog)
Type CW - engine with a vertical cylinder, air cooling, with a long crankcase (for example, Booster, BW’s, Stunt, Slider, Amico, SR until the 98th year)
Differences: the crankshaft on the CW model is different from the CY, CA, MY, MA models.
Cylinder: MA and CA models have the same liquid-cooled cylinders. MY and CY models have the same air-cooled cylinders.
CVT: all parts of the variator are identical for all types.
Clutch: the old (until the 98th year) clutch drum has a diameter of 105mm. New - 107mm.
CVT belt: MA, MY and CW models have the same belt. On the CA and CY models, oddly enough, it is longer due to the different gearbox cost - the clutch shaft for the CA and CY models is located farther relative to the crankshaft than for the MA, MY and CW models.
Standard belt sizes:
CA, CY - 16.5 x 792 mm
MA and MY - 16.5 x 747 mm
Transmission: MA, MY and CW have the same transmission and cover. The transmission of CA and CY motors differs from the MA, MY, and CW motors due to differences in wheel sizes and gear ratios. Their lid is also different.
Ignition: Minarelli engines are equipped with two different ignition systems - Yamaha and Ducati. In a Yamaha ignition system (Aprilia, MBK, Yamaha), the CDI and voltage regulator are separate parts. In a system from Ducati (Malaguti, KTM), these two devices are combined into one unit.