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Naraku QMB139 52.4mm Performance Cylinder & Head Kit

SKU: 137-4

This item is IN STOCK

Current Stock: 15

Naraku 50cc QMB139 4-stroke 52.4mm, Racing Big Bore Cylinder and Head Kit. Kit includes cylinder, piston, rings, piston pin, cir clips, cylinder head, head gasket, and base gasket.

When used in conjunction with a stock stroke of 41.4mm the total displacement comes out to 89.3cc! When used with a 44mm stroker crank, total displacement measures 94.9cc!

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Please note: replaces Cylinder Heads with 64mm Valves (Short Valve Style). Please see Related Items if you need 64mm valves. You may need to modify your engine case to accommodate the larger cylinder.

  • Upgrades to 89.3cc
  • Cylinder Bore: 52.4mm
  • Cylinder Sleeve Outer Diameter: 54.4mm 
  • Wrist Pin Diameter: 13mm
  • Total Piston Height: 36.3mm
  • Compression Height (from center of wrist pin hole to top edge of piston): 20mm
  • Non-emissions style head
  • Intake valve: 23mm
  • Exhaust valve: 20mm
  • Intake Port Diameter: 20.8mm
  • Exhaust Port Diameter: 18.7mm
  • Uses Short 64mm Valve Stems
QMB139 50cc/49cc , Various unlisted makes/models