Malossi MHR 177 – Aluminium cylinder for advanced Vespa setups
Malossi has expanded its cylinder range for Vespa Largeframe engines with 125–150 cc (Sprint, PX, Cosa, LML) to include three new versions: Sport 177 cc, MHR 177 cc and MHR 187 cc.
These are completely new designs and have nothing in common with their older 166 cc cast iron predecessor. The use of aluminium makes the kit more thermally stable and allows for a Ø63 mm bore. Externally, the cylinders are almost identical. All three versions use the same cylinder head and the same piston (the Sport version has two piston rings). The formerly patented CVF II system has been dropped in favour of significantly enlarged transfer ports. To unlock full power and torque, engine casing modifications are required.
MALOSSI 177 MHR57
The MHR series is aimed at experienced tuners looking to get the maximum out of their engine. A solid understanding of thermodynamic and mechanical engine principles is assumed. A great feature is the bolt-on exhaust flange, which allows further tuning of the exhaust port and significantly boosts performance. Malossi states an output of 21–28 hp in stock form.
- Stroke x Bore: 57 x Ø63 mm
- Displacement: 177.59 cm³
- Exhaust timing: 178.2°
- Transfer timing: 119.2°
- Blowdown angle: 29.5°
- Squish clearance: 0.7 mm (piston sits 0.2 mm below TDC)
- Compression ratio: 1:11.25
- Transfer ports: 7
- Piston rings: 1
- Ignition timing: 18° BTDC
We recommend modifying the rotary valve intake or – for better performance and rideability – switching to a reed valve intake system. For exhaust systems, the BGM BigBox Sport or RR Box are ideal matches, as they support the cylinder’s power band extremely well.
Also available in a 60 mm stroke version.
NOTE: The tall bolts on the exhaust flange may interfere with the header clamp. It’s best to replace them with flat-head bolts from the start (Item no.: 3333891)
(US211118)
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