DR177 HP aluminum cylinder for Vespa PX, Sprint and GTR
CYLINDER DR177 HP ALUMINIUM FOR VESPA PX125/150, Sprint 150 Veloce, GTR125, Cosa125/150
The DR177 HP aluminum is a completely new design and has nothing to do with the well-known DR177 made of cast iron. It has a modern cylinder layout with four main scavenging ducts and two support ducts. The outlet is one-piece (DR177 gray cast iron = three-piece). The exhaust flange is made of steel and is screwed on with four screws, making it replaceable.
The cylinder head has cooling fins on the underside, but still has a decentralized combustion chamber. The piston has two 1.0 mm thick steel piston rings.
- Displacement: 177cc
- Stroke: 57 mm (standard)
- Bore: Ø63mm
- Control angle overflow/exhaust: 124°/177°
- Compression ratio: 10.5:1 (eff.6.7:1)
- Ignition timing: 18° v.o.t.
- Pinch point: 1.2-1.4 mm
- Spark plug: B9HS/W2AC
The timing angles are clearly different from its predecessor and, at 124°/177°, are already sporty for a touring cylinder. If the cylinder is to be used with a long-stroke shaft (60 mm stroke), the control angles are already very high (129°/179°). This means that the overcurrent angle is clearly too high for a touring engine based on a rotary valve. We therefore recommend the use of a 57 mm stroke (as standard) crankshaft. The compression ratio of 10.5:1 (effectively 6.7:1), on the other hand, is moderate and, in conjunction with the aluminum cylinder base, provides a healthy basis for a touring engine.
CONCLUSION: With the new DR177 HP Aluminum, DR offers a modern successor to its popular classic. The DR177 HP Aluminum is thermally more stable, more wear-resistant, more powerful and requires less maintenance (no clogged secondary outlets that need to be cleaned).
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