The classic Vespa two-stroke engine, particularly models from the 1960s through the 1990s (Vespa VNB, VBB, Super, PX, and smallframes like the PK), uses a magneto flywheel ignition system. Timing is set by adjusting the stator plate relative to the crankshaft’s rotation. Unlike modern vehicles with electronic control units (ECUs) and fixed timing maps, the Vespa’s contact breaker (points) system or early electronic ignition (e.g., Ducati Energia) relies on mechanical precision. The factory specification for ignition advance is usually given in millimeters before top dead center (BTDC) measured at the piston’s travel, or—more universally—in degrees of crankshaft rotation before TDC. For example, a Vespa PX200 may require 23° BTDC at idle.
To measure degrees directly on the engine, a mechanic needs a circular scale fixed to the crankshaft. This is the disco graduato. Traditionally, these were metal discs with laser-engraved markings, sold as part of specialist toolkits. However, their cost and scarcity drove home mechanics to craft their own—using printed paper circles glued to cardboard, then attached to the flywheel side of the crankshaft.
Design:
Save as PDF:
Il mercato è pieno di dischi graduati in alluminio o plastica rigida, ma presentano tre problemi: disco graduato vespa da stampare pdf
Utilizzare un PDF da stampare risolve tutti questi problemi:
Creating a disc is not merely a matter of drawing a circle; it requires mathematical precision to ensure the needle points to the correct speed. Design:
Per utilizzare il disco sulla tua Vespa hai due opzioni:
The disc is designed with the following features: Save as PDF:
| Feature | Specification | | :--- | :--- | | Diameter | 150 mm (optimal for adhesion to flywheel or magnetic holder) | | Scale Range | 0° to 360° (full circle) | | Precision | 1-degree increments | | Key Markers | TDC (Top Dead Center – marked "PMS" or "TDC"), advance marks (10°, 15°, 18°, 20°, 23°, 25°) | | Rotation | Marked clockwise (CW) and counterclockwise (CCW) for 2-stroke engines | | Language | Italian/English (PMS = Punto Morto Superiore / TDC) |
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