Vespa Quattrini M244 engine 252ccm - from super tourers to top racers
The story of the Quattrini cylinder
Towards the end of 2015, rumors grew that Max Quatrini launches a potent cylinder for the PX200.
The time has come at the beginning of 2016. The M232 and the big brother M244 are available on the market.
A construction that took some getting used to seemed to follow the concept, a cylinder with a maximum bore of 72mm in the M244 and without a supporting cylinder base.
Due to the design of the crankshaft by Quattrini, with a connecting rod of 126mm, which is rather long for the Vespa engines, the piston does not work so deep in the engine housing and therefore does not need a long, classic cylinder base.
Today, in 2021, the cylinder is enjoying increasing popularity due to its very high torque values and the smooth-running design 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 carburettors for you in various stages of expansion.
In the delivery note attached here for our technology department, you will find all the components that we have used for this engine and that, in our opinion, function permanently with this concept.
200 test runs on our test bench
In total, we have over 200 test runs with the Quattrini M244 Completed on our P4 test bench with various engine expansion stages. We have more than 50km measured runs documented and almost 20 liters of fuel burned.
We would like to share the experiences gained from this test with you in this blog series.
To select the parts:
The expected high torques of the M244 speak in any case for a reinforced motor housing.
The experience from many kilometers on the road with our own scooters has taught us that engines in the range from 22 to 25 HP can be implemented as "durable" in conjunction with a Piaggio engine housing.
The Displacement of over 220ccm at erhigher engine speed, can no longer be supplied with sufficient fresh gas via a classic rotary valve on the narrow Vespa crankshaft. That's why we choose this Malossi motor housing with membrane control .
To make the fuel mixture we have one Polini 30mm carburetor used. In this experiment he stands for one Carburettor with 30mm bore. In the course of the tests, we also tried a PHBH30 in a counter-test. We will present the result of this in the following part of this blog series.
On the topic crankshaft we trust king wave. Here we find exactly what we are looking for to build a high-torque, smooth-running and durable engine.
The choice falls on one king wave with 62mm stroke and 128mm connecting rod. Due to the 2mm longer connecting rod and increased stroke, we have the opportunity to work with the control angles by moving the cylinder using spacers on the cylinder head and the cylinder base in the stroke direction. The longer connecting rod in connection with the weighty crankshaft also brings a significant plus in smoothness.
The stroke of 62mm results Cubic capacity 252,4ccm - already very promising to build a torque-oriented engine.
The performance of the 252ccm unit is controlled by a bgm superstrong Clutch, the bgm primary 25-62 and one bgm Transmission with the graduation 12-13-17-20 passed on to the rear wheel. The short, fourth gear on the auxiliary shaft keeps the most frequently used gear more stable. With one tooth less in fourth gear, the teeth become significantly wider in the tooth base and thus offer a significantly higher load capacity than the variant with a gear wheel 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 to a sporty design. Just to be able to depict a section through the possible variants. As a starting point for the test series, we set a basis with small control angles in order to be able to test as many sensible variants as possible later
To determine a starting point, the crankshaft is mounted with bearing dummies and the cylinder is attached to determine the control angle.
Based on this initial data, we can consider to what extent we can sensibly set up the cylinder with spacers and work on the outlet in later stages of expansion.
After measuring back and forth a bit, we decide to start from the middle position of the control angle with one Transfer angle of 124 ° and a Outlet angle of 177 °.
Assembling the engine
Dream team: Malossi | bgm PRO | Kingwelle | Quattrini
The factory new Malossi motor housing will be finished by king wave 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 with a very tight tolerance.
We also offer the completely machined housing with a high-quality crankshaft from Kingwelle as a set. We use the set for this engine KWM46228.
The one attached by Malossi Bearing Kingwelle does not recommend 6205 for the alternator side. We follow Kingwelle's recommendation and use a here NU205.
Before inserting the bearings, we process the motor housing and adapt the cylinder and the overcurrent ducts to each other. On a Piaggio engine case, this tends to degenerate into an evening event. The Malossi housing is already designed for the channels of the Malossi Sport and MHR cylinders and requires little rework for the Quattrini M244. Most of the work goes into removing the sealing surface on the cylinder base, which allows the M244 to be used on Piaggio engine housings.
Adjusting the transfer channels to the motor housing is done quite easily. The cylinder base seal shows how little needs to be adjusted here.
All bearings are traditionally used by shrinking in order to avoid damage to the bearing seats by simply pulling in the bearings. The shrinking or cold / warm process offers the advantage that no mechanical stress acts on the surface of the bearing seats and the seat is not widened as a result.
Wandering Malossi engine cases
Another peculiarity of the Malossi motor housing is that the supplied original silent rubbers are too narrow for the motor housing. Or rather, here Malossi has simply oriented the seats for the silent rubbers deeper in the housing than was originally the case. This allows the motor housing to move over the silent rubbers in the direction of the frame.
The M244 with a 62mm stroke of the king shaft brought to 252ccm, will transfer a lot of torque to the rear wheel. A guarantee to achieve a high cruising speed at a reduced speed. That enables the primary. Starting from a massive and early onset of torque mountain, the primary can be selected to be long or even very long. With 25 to 62 teeth, we use the longest primary offered by bgm. The reinforced primary repair kit from bgm creates a durable primary drive.
Shift pins and crossbar are included threadlocking assembled.
The bgm secondary gear is set with the smallest possible clearance with the bgm shoulder rings.
Assemble the Malossi motor housing
Further adjustments to the motor housing are no longer necessary and all other innards find their way into their place.
To assemble the crankshaft, the shaft sealing ring is moistened with a little oil so that the sealing lips slide cleanly onto the crankshaft and are not damaged.
The Malossi engine case, contrary to the Piaggio engine case, is without a solid seal composed. Instead of the paper seal, as in a modern engine concept, the housing is Surface seal sealed.
To connect the housing halves, Malossi uses M8 hexagon socket screws. Due to the different lengths of the screws used, a look at the Application listto find the correct attachment point.
bgm PRO Superstrong clutch & King shaft
The King Shaft is supplied with its own thrust washer and special key. The thrust washer has a clear radius that fits exactly to the radius of the crankshaft. A breaking thrust washer is almost impossible.
The Kingwelle has a special feather key on the drive side, which is specially manufactured for Kingwelle and fits exactly into the groove of the coupling hub.
We use one as a coupling bgm Superstrong CR a. With the standard equipment, 10 bgm springs XL, the CR clutch manages a reliable transmission of power up to 40hp. The king shaft coupling nut has a fine thread of the dimension M12x1. The nut comes with screw lock and a Tightening torque of 70Nm attached.
Assembly of further components
The engine is then completed with the rest of the components.
Intake manifold with the Malossi 2-valve membrane. Clutch cover, switch latch, cover for the starter motor and the bgm ignition system with static ignition timing.
Stress-free assembly of the ignition base plate on Malossi engine housings
The Malossi motor housing is reinforced in many places. This can lead to contact between the base plate and the bearing seat when the ignition is installed. The base plate of the ignition must sit tension-free in the centering, so in individual cases the base plate and / or the motor housing must be slightly reworked to ensure a tension-free fit of the base plate.
Check crush dimension
Before the final assembly of the cylinder, we check the pinch size using solder.
Due to the increased stroke, we aim for the squeeze dimension in the range from 1.3mm to 1.4mm and set this using the enclosed cylinder base seals.
By compensating for the larger stroke, there is no need for centering on the cylinder head. For this reason, holes for fitting sleeves are made in the cylinder head and cylinder. The adapter sleeves prevent the spacers used for the cylinder head in the course of the test from protruding into the combustion chamber and causing unwanted damage there.
The new Quattrini engine on the test bench
For the test runs, we set the ignition to 19 ° BTDC.
The runs of the first expansion stage We will introduce M244_1 to you in the next blog post before…
Just a quick note - none of the runs were below the 30PS Mark on the unprocessed M244