• NK100.81
• Heavy Duty
• 16 Tooth Oil Pump Drive Gear
• Includes Bearings
• Made in Taiwan

• Piston Diameter: 61mm
• Piston Type: Forged
• Compression Ratio: 11.5 to 1
• Piston Compression Height: 19.5mm

• Only for use with part #169-99
• Exhaust Valve Diameter: 22.8mm
• Exhaust Port Diameter: 22mm
• Exhaust Port Bolt Hole Spacing: 50mm
• Intake Valve Diameter: 27.75mm
• Intake Port Diameter: 23mm
• Intake Port Bolt Hole Spacing: 45mm
• 57mm “B-case” stud spacing
• Overall Height: 66mm

We recommend that you use our QMB139 performance cylinder head (see Related Items) with this set as some stock cylinder heads will not fit.

• Upgrades to 80cc
• Cylinder Bore: 50mm
• Cylinder Sleeve Outer Diameter: 54.9mm
• Wrist Pin Diameter: 13mm
• Total Piston Height: 34.8mm
• Compression Height (from center of wrist pin hole to top edge of piston): 18.3mm

• Includes Drilled and Friction Enhanced Clutch Bell
• Clutch Bell Inner Diameter: 112mm
• Pulley Outer Diameter: 115mm
• Clutch Inner Diameter: 12mm
• Number of Splines: 16
• 1500RPM Clutch Springs
• 1500RPM Torque Spring

• Exhaust Valve Diameter: 23mm
• Intake Valve Diameter: 27.75mm
• Exhaust Port Diameter: 26.5mm
• Intake Port Diameter: 27.5mm
• Overall Height: 60mm