Vespa Quattrini M244 engine 252cc - from super tourer to top racer
The story behind the Quattrini cylinder
Towards the end of 2015, rumors began to circulate that
Max Quattrini would launch a potent cylinder for the PX200. The time came at the beginning of 2016. The M232 and its big brother, the M244, are available on the market. At first, the concept seemed to take some getting used to: a cylinder with a maximum bore of 72 mm for the M244 and without a supporting cylinder base. Due to the design of the crankshaft by Quattrini, with a rather long connecting rod of 126mm for Vespa engines, the piston does not work so deep in the engine housing and therefore does not require a long, classic cylinder base. Today, in 2021, the cylinder is enjoying increasing popularity due to its high torque values and smooth running thanks to the long connecting rod of the Quattrini crankshaft. Reason enough for us to build an engine with it and play through many possible scenarios for you and see what comes out of it. We have tested exhaust systems and carburetors for you in various expansion stages. In the attached delivery bill for our technical department, you will find all the components we have used for this engine and which, in our opinion, will work permanently on this concept.
200 test runs on our test bench
We have completed a total of over 200 test runs with the Quattrini M244 on our P4 test bench with various engine configuration levels. We documented
more than 50 km of measured runs and burned almost
20 liters of fuel. We would like to share the experience gained from this test with you in this blog series.
About the choice of parts:
The expected high torques of the M244 definitely speak in favor of a reinforced engine housing. Experience from many kilometers on the road with our own scooters has taught us that engines in the 22 to 25 hp range can be considered "durable" in combination with a Piaggio engine housing. Our
M244 Quattrini cylinder is to be expanded somewhat in the course of the test. Therefore, the choice here falls on an engine case from
Malossi with reed valve intake. A
displacement of over 220cc with
increased power output can no longer be supplied with sufficient fresh gas via a classic rotary valve on the narrow Vespa crankshafts. That's why we choose the
Malossi engine case with diaphragm control from. To produce the fuel mixture, we used a
Polini 30mm carburetor was used. In this test, it is representative of a
carburetor with a 30 mm bore. In the course of the tests, we also tried out a PHBH30 in a counter-test. We will present the results in a subsequent part of this blog series. When it comes to the
crankshaft, we rely on
crankshaft. Here we found exactly what we were looking for to build a high-torque, smooth-running and durable engine. The choice falls on a
King shaft with 62mm stroke and 128mm connecting rod. Thanks to the 2mm longer connecting rod and increased stroke, we have the option of working with the control angles by moving the cylinder in the stroke direction using spacers on the cylinder head and cylinder base. The longer connecting rod in conjunction with the heavier crankshaft also provides a significant increase in running smoothness. The 62mm stroke results in
a displacement of 252.4cc - already promising for building a torque-oriented engine. The
ignition should keep our Tourer running smoothly, so we chose the
bgm ignition with the
PX pole wheel with a mass of 2300g. The power of the 252cc engine is transmitted via a
bgm Superstrong clutchthe bgm primary 25-62 and a
bgm gearbox with a gear ratio of 12-13-17-20 to the rear wheel. The short fourth gear on the auxiliary shaft keeps the most frequently used gear more stable. With one less tooth in fourth gear, the teeth are significantly wider in the tooth base and therefore offer a significantly higher load capacity than the variant with a gearwheel with one more tooth.
Concept and test plan
The requirement for the test setup is that we work from a rather good-natured touring design towards a sporty design. In other words, to be able to map a cross-section of the possible variants. As a starting point for the test series, we define a basis with low control angles in order to be able to test as many sensible variants as possible later on. To define a starting point, the crankshaft is mounted with bearing dummies and the cylinder is fitted to determine the control angles.
Based on this initial data, we can consider to what extent we can usefully set up the cylinder with spacers and, in later stages, work on the exhaust.
After a bit of measuring back and forth, we decide to start from the middle position of the control angles with a
transfer angle of 124° and an
exhaust angle of 177°.
Assembly of the engine
Dreamteam: Malossi | bgm PRO | Kingwelle | Quattrini
The brand-new
Malossi engine housing is supplied ready-machined by
Kingwelle for the crankshaft with 62mm stroke and the enlarged diameter of the crank webs with 99.4mm. The bearing seat for the bearing on the alternator side is also checked and reworked in individual cases, as the bearing seat is manufactured by Malossi to a very tight tolerance at the factory. We also offer the finished housings with a high-quality crankshaft from Kingwelle as a set. For this engine we use the set
KWM46228. The 6205
ball bearing supplied by Malossi for the alternator side is not recommended by Kingwelle. We follow Kingwelle's recommendation and use an
NU205. Before fitting the bearings, we machine the engine housing and adapt the cylinders and the overcurrent channels to each other. On a Piaggio engine case, this often turns into an evening-long event. The Malossi housing is already designed for the Malossi Sport and MHR cylinders and requires little reworking for the Quattrini M244. Most of the work is required to remove the sealing surface on the cylinder base, which allows the M244 to be used on Piaggio engine cases.
Adapting the transfer channels to the engine housing is quite simple. The cylinder base gasket shows how little needs to be adjusted here.
All bearings are fitted in the classic way by shrinking to avoid damaging the bearing seats by simply pulling in the bearings. The shrinking or cold/warm process offers the advantage that no mechanical load is applied to the surface of the bearing seats and the seat is not widened as a result.
Moving Malossi engine cases
Another peculiarity of Malossi engine cases is that the original silent rubbers supplied are too narrow for the engine case. To be more precise, Malossi has simply positioned the seats for the silent rubbers deeper in the housing than is the case with the original. This allows the engine housing to move over the silent rubbers towards the frame. Quite some time ago, we used a
spacer set BGM7952SP spacer set for the silentblocs, thus ensuring that the silentblocs are securely seated in the correct position.
The gearbox
The M244 with 62mm stroke of the king shaft brought to 252ccm will transfer quite a lot of torque to the rear wheel. A guarantee for achieving a high cruising speed at reduced revs. This is made possible by the primary. Starting from a massive and early onset torque mountain, the primary can be chosen long, even very long. With 25 to 62 teeth, we use the longest primary offered by bgm. With the reinforced primary repair set from bgm, a durable primary drive is produced.
The shift bolt and shift cross are secured with
screw lock mounted.
The bgm secondary gearbox is adjusted with the smallest possible air clearance using the bgm shoulder rings.
Assembling the Malossi engine housing
Further adjustments to the engine housing are no longer necessary and all the other internals find their way into place.
To fit the crankshaft, the oil seal is moistened with a little oil so that the sealing lips slide cleanly onto the crankshaft and are not damaged.
Unlike the Piaggio engine cases, the Malossi engine case is assembled
without a solid gasket. Instead of the paper gasket, the housing is sealed with a
flat gasket, as in a modern engine concept.
Malossi uses M8 hexagon socket screws to connect the housing halves. Due to the different lengths of the screws used, a look at the
usage listto find the correct fixing point.
bgm PRO Superstrong clutch & crankshaft
The crankshaft is supplied with its own thrust washer and special feather key. The thrust washer has a clear radius that fits exactly to the radius of the crankshaft. This makes it almost impossible for the thrust washer to break.
The King shaft has a special feather key on the drive side, which is manufactured specifically for the King shaft and fits exactly into the groove of the clutch hub.
The clutch we use is a
bgm Superstrong-CR as the clutch. With the standard equipment, 10 bgm XL springs, the CR clutch can safely transmit power
up to 40 hp. The clutch nut of the king shaft has a fine thread of M12x1. The nut is fastened with threadlocker and a
tightening torque of 70 Nm.
Assembly of other components
The engine is then completed with the remaining components. Intake manifold with the Malossi 2-valve diaphragm. Clutch cover, gearshift detent, cover for the starter motor mount and the bgm ignition system with static ignition timing.
Stress-free installation of the ignition base plate on Malossi engine housings
The Malossi engine housing is reinforced in many places. This can lead to contact between the base plate and the bearing seat when fitting the ignition. The base plate of the ignition must sit in the centering without tension, so in individual cases the base plate and/or the engine housing must be slightly reworked to ensure a tension-free fit of the base plate.
Check the crush dimension
Before finally fitting the cylinder, we check the crush dimension using solder. Due to the increased stroke, we aim for a crush dimension in the range of 1.3mm to 1.4mm and adjust this using the enclosed cylinder base gaskets.
By compensating for the increased stroke, centering on the cylinder head is no longer necessary. For this reason, holes for locating sleeves are drilled in the cylinder head and cylinder. The fitting sleeves prevent the spacers used for the cylinder head during testing from protruding unintentionally into the combustion chamber and causing unintentional damage.
The new Quattrini engine on the test bench
For the test runs, we set the ignition to 19° from TDC. The runs of the first expansion stage
M244_1 will be presented in the next blog post ... Just a quick note - none of the runs were below the
30hp mark on the
unfinished M244
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