Top Performances 85cc Big Bore Kit 49.5mm – Minarelli AM6 – Cylinder + 44mm Crankshaft

The Top Performances 85cc Big Bore kit is a complete high-performance setup for Minarelli AM6 (AM5/AM6) manual engines. This kit combines a 49.5mm cast iron cylinder with a 44mm stroke crankshaft, resulting in approximately 85cc displacement.

Thanks to the longer stroke and larger bore, this setup delivers significantly more torque and power compared to standard or 70cc configurations. When combined with a 21mm carburetor and a racing exhaust, this kit can reach approximately 17–18 hp.

The cast iron construction ensures durability and long service life, even under high-rev racing conditions.

Technical specifications:

• Brand: Top Performances
• Type: Big Bore kit
• Displacement: 85cc
• Bore: 49.5 mm
• Stroke: 44 mm
• Cylinder material: Cast iron
• Wrist pin: 12 mm
• Exhaust port: Oval
• Tuning level: Racing
• EAN: 9921450

Timing & setup data:

• Exhaust timing: 191°
• Inlet timing: 132°
• Squish clearance: 0.9 ± 0.1 mm
• Compression ratio: 8:1
• Recommended ignition advance: 17° (1 mm before TDC)
• Recommended spark plug: NGK BR10EG

Supplied including:

• 49.5mm cast iron cylinder
• 1-ring domed piston
• Modular cylinder head
• 28/25 mm reducer bush
• Cylinder gaskets
• 44mm stroke crankshaft
• Small end bearing

Note: Crankshaft bearings and oil seals are not included. Two different bearings are required (6303 and 6204).

Fitment:

Minarelli AM5 / AM6 50cc 2-stroke engines.

Spare parts:

49.5mm piston:

Top Performances 49.5mm Minarelli AM6 Piston

Also known as Top Performances 85cc AM6 kit, TP Big Bore 49.5mm AM6 cylinder + crankshaft or Minarelli AM6 44mm stroke racing kit.