Vespa Prim 125 ET3 PK 125 MALOSSI 136cc MHR Alloy Cylinder Kit

Vespa Prim 125 ET3 PK 125 MALOSSI 136cc MHR Alloy Cylinder Kit

With the 136cc MHR, Malossi launches a completely new version of the popular smallframe cylinder for PV, ET3, PK125, ETS. With significantly larger channels, a much more modern flushing system and made of coated aluminium, it provides good conditions for lasting top performance.

The cylinder can be operated either as a housing suction device (rotary vane or diaphragm) or, by means of an optionally available diaphragm suction port, as a direct suction device.

• Aluminium cylinder with coated raceway
• centred cylinder head with O-ring seal
• new piston type with one piston ring
• larger inlet
• three-part outlet
• modified overflow channels

Thanks to the now used aluminium material and hard chrome coating, the cylinder is also thermally resistant to higher performance requirements. The inlet area and the volume of the overflow channels as well as the intake area has grown significantly.

Malossi gives a geometric compression ratio of 12.5:1 for the MHR.
The combustion chamber is offset by 0.6mm from the cylinder head sealing surface. Also with the MHR a perfect sealing to the combustion chamber is guaranteed by a 1,75mm thick O-ring and centered very cleanly over the cylinder bore by 4 points. Besides the channel cross sections Malossi also did something to the control angles. With an assumed piston clearance of 1mm, the MHR with 51mm stroke offers with 124° to 179° already quite sporty steering angles.

The resulting forward exhaust of 27,5° and the larger surface by the side outlets, also appeals to performance-oriented exhaust systems. With an outlet diameter of 28mm and a stud spacing of 56mm, many common sporty exhaust systems fit.

With the press presentation Malossi advertises the new MHR for the Vespa, depending on the exhaust system, with a performance of 18-25HP. We see the MAlossi MHR 136 as the perfect entry for a sporty oriented engine. Without any further machining the cylinder already delivers good power and torque values which, due to further components and machining, still allow a lot of air to rise.

details at a glance

piston

• new type with stable piston shirt
• one piston ring 1mm
• 181,5gr

cylinder

• aluminium with hard chrome coating
• overflow channels MHR
• larger inlet area
• bore 57,5mm
• stroke 51mm
• conrod 97mm
• three outlet channels
• outlet Ø 28mm
• stud distance outlet 56mm / M8
• stud distance inlet 65mm / M6
• cylinder base gasket 0,5mm
• control angle 124° / 179° (41mm/ 30mm)

cylinder head

• centering over 4 points
• O-ring seal 1.75mm
• CNC machined combustion chamber
• compression ratio 12.5:1

accessories (included)

• cover for direct inlet
• gaskets for direct and housing inlet
• stud bolts for inlet and outlet
• gasket set cylinder, O-ring 1.75mm, foot seal 0.5mm

NOTES:

• Due to the larger overcurrent channels, the motor housing must be adapted according to the enclosed Malossi instructions.
• The stable rectangular ring should be installed with the inscription facing the piston top.

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