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S p e c s: VMA1M Motorinduction: disc valve bore: 55 mm stroke: 51 mm cubic capacity: 121.1 cc compression ratio: 8.2: 1 bhp at rpm: 5.6 @ 5500 con rod length:97mm piston compression height: 36mm piston type: domed small end diameter:19mm big end diameter:20mm flywheel side bearing: N204ECP (2 piece) flywheel side bearing: 6024 (1 piece) drive side bearing: 6303 clutch bearing: 16005 input shaft bearing: (flywheel side): 6200 output shaft bearing (flywheel side): rear wheel bearing: 6204 flywheel side oil seal: 19x32x7 drive side oil seal: 22.7x47x7/7.5 rear hub oil seal: 27x37x7 Vespa 125 Links: VMA2T overview VMA2T electrical page Engine Work |
Casings:
The crankcase mouth is
61mm to accept all kits. The 19mm intake manifold is attached with only
two studs compared to 3 studs on later PK models Bearings: Early motors had one piece bearings on
both sides of the crank which are a pain when splitting the casings.
The one piece flywheel side bearing can be replaced with a two piece to
make splitting the casings easier in the future. Use an SKF N204ECP for the conversion Cranks: Any smallframe crank can be installed in
this engine. Popular changes are to install a PKXL or PK125ETS crank
which allows use of many different flywheels. Flywheel side bearings
and seals will differ for these conversions. Standard barrel:
The original Primavera barrel has
only two opposing ports in the barrel. The later Primavera ET3 barrel
& piston has three ports and can be used on earlier models as the
third port is completely contained within the barrel casting (i.e. no
casing modifications are necessary.. Both the barrel and the piston
will have to be replaced for this conversion. Kits: Any
small frame kit can be used on this motor. Ignition: The original 6V points can be replaced with a 12V
electronic set up off a later Primavera ET3 or any of the PK range
systems. The flywheel and stator off an ET3 bolt right on, but many PK
flywheels use a different taper. Check here for a guide to smallframe
cranks. Gearbox: Any
smallframe gearbox will fit in the casings but almost all the parts
will have to be replaced. |
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