Adapter plate set for converting Malossi 210 sports cylinders to Vespa 80-150cc Largeframe engine cases
Which rider of a Vespa with only 80cc or 125cc has not dreamed of experiencing the torque and superiority of a 200cc engine in their vehicle? Enjoying a pass road powerfully and casually without constantly having to use the lower gears? More power and still have the full reliability of a 200cc engine?
All this is now possible on the basis of an existing 80-150cc engine. This set is based on the powerful Malossi 210 cylinder, which is additionally combined with an extended stroke of 60 mm. This results in a whopping 221 cc, from which the engine can generate over 20 hp and 22 Nm and more without much effort.
The adapter set is suitable for the following vehicles:
- Vespa Sprint Veloce150 (VLB1T 294260-)
- Vespa GTR125 (VNL2T 145901-)
- Vespa Super150 (VBC1T 412374-)
- Vespa TS125 (VNL3T 18139-)
- Vespa PX80 (V8X1T), PX125 (VNX1T, VNX2T, ZAPM093), PX150 (VLX1T, ZAPM74, ZAPM094)
- Vespa Cosa125 (VNR1T), Cosa150 (VLR1T)
- LML125/150 2-stroke
- Star/Stella 125/150 2-stroke
Based on an idea by Geoff (J&G 2% Vespa Tuning) and the technical implementation by W.T., we subjected the set to an extensive and lengthy stress test on the road and highway. The result is so convincing and reliable that we can now offer it as a set for the experienced mechanic. It allows the use of a Malossi 210 sports cylinder of the PX200/Rally/Cosa models on the engine cases of the Vespa Largeframe models from 1977 onwards. From this date onwards, the engine cases were converted to three overcurrent channels or to the crankshaft of the PX models (for vehicles before 1980, pay attention to the frontier chassis number). In general, the set fits every engine with three overcurrent channels and the PX crankshaft type (recognizable by a pole nut with M12 thread).
The adapter set includes:
- 1x crankshaft BGM031125G 60 mm stroke, connecting rod=125 mm
- 1x adapter plate steel 14 mm
- 1x aluminum spacer 1.5 mm
- 4x stud bolts M8x165mm
- 4x screws M7x25mm
To convert this engine to 221cc, the following is required in addition to the adapter set:
- Malossi 210cc cylinder incl. cylinder head (M3118591)
- Exhaust PX200
- Longer gear reduction
- Reinforced clutch
ADAPTER-SET
The conversion is based on a crankshaft with a 20mm longer connecting rod (125mm instead of 105mm).
The solid CNC-milled steel adapter plate is screwed onto the engine housing and accommodates the stud bolts for the PX200 cylinder. A 1.5mm thick aluminum gasket between the adapter plate and cylinder base seals the bolt holes and ensures the correct installation height.
MALOSSI SPORT
The SC80210 adapter set is designed for use with a Malossi Sport 210 cylinder. However, it is essential that the engine case is spindled out as the Malossi cylinder base cannot be shortened without losing stability. In conjunction with an adapted engine housing (intake, transfer ports), the use of an SI24 carburetor and a good box (Polini, BBT V2 etc.), the engine delivers over 20 hp/22 Nm with a very nice speed range and high torque at an early stage.
CURBSHAFT/ INLET
The BGM crankshaft fits into the engine housing of the PX80-150cc models without any modifications.
It has adapted timing angles and harmonizes perfectly with the intake of the PX80-150cc models. Due to the lower pre-compression, the converted engines work more harmoniously with shorter intake angles. This means that the intake control angles of 120° f.o.t. to 70° n.o.t., which are otherwise obligatory for sports engines, are not absolutely necessary for good performance. Tests on our engines have already produced very good results with 115°/60°.
VERGASER
The standard carburettor (SI20/20D) can be retained, provided it is adapted by the jetting (use the basic tuning of the PX200). However, the carburetor of the PX200 models (SI24/24E) provides more power and torque. This also has the appropriate jetting. To fit the SI24 carburettor, the carburettor bowl should be adapted in the passage (this can be done quickly with a file or a Dremel/Proxxon tool).
GEARBOX
To make good use of the significantly higher and early torque, the reduction ratio should be extended:
80 ccm
The PX80 has its own secondary gearbox, which is very short (originally, the third gear of the PX200 already has a longer reduction ratio than the fourth gear of the PX80! If the PX80 gearbox is to be retained, it can be used with an extra-long reduction primary from e.g. BGM (25/62). This is used in conjunction with a stable clutch of type COSA2, e.g. a BGM Superstrong clutch. Alternatively, a gearbox from the PX125/150 models can also be used in the PX80 engine housings with minor conversion work.
To do this, either the diameter of the auxiliary shaft axle on the alternator side is turned down or the engine housing is enlarged at the mount for the auxiliary shaft (remove the existing bushing).
125/150 cc
For 125/150 cc engines, it is sufficient to change to the components of the 200 cc engines on the primary side (primary wheel 64 (BGM) or 65, clutch pinion 23 or 24 (BGM) teeth).
CL
UTCH
The 80-150 cc models up to model year 1998 still use small clutches with 6 springs (108 mm basket diameter). These cannot cope with the high torque of 200cc engines in the long term. They should therefore be replaced with a corresponding clutch for 200cc models. A good option is to change directly to the most modern clutch type of the COSA2 models. The BGM Pro Superstrong is a very high-quality and stable clutch that is also easy to operate.
IGNITION/POLYWHEEL
These can easily be taken over from the donor engine. The ignition setting is adjusted according to the cylinder (18°-23° FDC). Of course, other ignitions/pole wheels can also be used for further tuning purposes. Our test engine ran with the BGM Touring pole wheel with 2300 grams, which harmonizes very well with the performance characteristics of the 200cc engines.
CYLINDERHAUBE
Due to the 15 mm increase in cylinder height, the cooling hood must also be extended accordingly. We simply used two hoods and cut off the lower third of one of them. We then connected this to the complete other hood using conventional self-tapping screws. Of course, this can also be done more easily, but for us this method has also proven itself in everyday use. Alternatively, the hoods can also be welded with a soldering iron. Special plastic welding rods are also available for this, but as a rule you can also use the remains of the sacrificed hood as filler material.
AUSPUFF
Due to the higher cylinder position, the exhaust may need to be adjusted. Our experience has shown that the Polini box systems have to be modified (twist the mounting brackets). The BGM Touring V2 systems (BGM1011TR2), on the other hand, worked on our setup without any adjustments.
CYLINDER DISASSEMBLY
Due to the raised cylinder, it is not possible to remove the cylinder head/cylinder while the engine is installed in the chassis. Alternatively, the stud bolts can be locked with our BGM72M7 tool and unscrewed from the adapter plate when the cylinder is fitted. In this way, both the head and the cylinder can be removed with the engine suspended in the frame. This procedure is not normally recommended, as the threads in the soft aluminum of the engine housing are not designed for frequent disassembly or assembly. The original stud bolts from Piaggio have a thickened thread on the side where they are screwed into the engine housing, which causes them to jam in the housing.
However, due to the other stud bolts we use and the steel adapter plate material, this is completely uncritical.
CONCLUSION
If you enjoy motor work and are not afraid of minor adjustments, you can build a powerful and durable motor with little effort without having to use a new motor housing.
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