Polini Evolution 86/100cc Exhaust Minarelli AM6

Polini Evolution Racing Exhaust for large-displacement Minarelli AM6 engines, developed to work with the Polini Big Evolution Cylinder ref. 133.1012 and Racing setups of approximately 86-100cc.

In a tuned 2-Stroke engine, the exhaust is a fundamental part of the setup. It does not merely evacuate gases: the shape and length of its cones generate pressure waves that help empty the cylinder and return part of the fresh mixture to the chamber before the exhaust port closes.

When we increase displacement, timing, and operating speed, an exhaust designed for 50/70cc quickly becomes a restriction. The engine needs a chamber with greater volume and geometry adapted to the gas flow moved by an 86-94cc Racing Cylinder.

The Evolution is designed precisely to work in that range. When the exhaust enters resonance, the waves generated by the chamber help improve cylinder filling, allowing the engine to come strongly into the power band and continue breathing at high RPM.

This also explains why it is not an exhaust intended for a small cylinder. An engine with low displacement or overly conservative timing does not generate the flow or operate in the range for which this chamber is designed, so the assembly may lose response and end up completely outside its operating zone.

The exhaust must work together with the rest of the engine. In a setup of this level, we recommend pairing it with a large-diameter carburetor, Racing intake, reinforced crankshaft, upgraded clutch, and correctly adjusted ignition. If one of these elements limits flow or operating speed, the engine will not be able to take full advantage of the expansion chamber.

Technical characteristics

• Manufacturer: Polini.
• Range: Evolution.
• Reference: 200.0422.
• Engine: Minarelli AM6 2-Stroke.
• Type: Racing expansion chamber exhaust.
• Recommended displacement: large-displacement Racing setups.
• Recommended Polini Cylinder: Big Evolution 94cc.
• Cylinder reference: 133.1012.
• Polini Cylinder diameter: 52 mm.
• Polini Cylinder stroke: 44 mm.
• Use: competition.

Compatible engines

• Minarelli AM6