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101-Octane Crankshaft 41.4mm 16T Stroker (139QMB)

101-Octane Crankshaft 41.4mm 16T Stroker (139QMB)

Description: 101-Octane Crankshaft 41.4mm Performance Stroker 16-Teeth for 130QMB 49/50cc 4-stroke engine. Standard stroke 41.4mm. When used in conjunction with a 52.4mm cylinder big bore, total displacement cranks out at a whopping 89.3cc!

The crank is pre-pressed with main bearings and a rod. 139QMB engines are factory-fitted with 2 different versions of the crankshaft. The only difference is the oil pump drive cog on the right-hand side (flywheel shaft). The old version, installed in almost all scooters, has a 16-teeth oil pump drive cog on the flywheel shaft. The new version has a 22-teeth oil pump cog on the flywheel shaft.

NOTE: This 101-Octane Crankshaft 41.44mm has the 16-teeth oil pump drive cog on the flywheel shaft which only works in conjunction with the 33-teeth oil pump and sprocket assembly. However, you can use a machine press to remove the 16-teeth oil pump cog from the flywheel shaft of the 101-Octane Crankshaft 41.44mm and machine press it with the newer 22-teeth oil pump drive cog to work with the newer 47-teeth oil pump and sprocket assembly. 47-teeth oil pump sprocket assembly or 33-teeth oil pump sprocket assembly and its related timing cover are not included, sold separately.

Temperature Modification May Be Required: You'll need to heat the aluminum crankcase area where the crankshaft bearing side will be placed, in order to immediately fit the frozen Crankshaft bearing, seating flush in place. Users assume full responsibility and risk doing so using this 101-octane Crankshaft.


Include the following Crankshaft stroker.

•   1x Crankshaft L: 247mm / Stroke L: 41.4mm
•   1x Piston Wrist Pin Slot ID: 13mm
•   1x Flywheel Shaft Thread: M10
•   1x Oil Pump Cog Teeth: 16
•   1x Flywheel Shaft Bearing OD: 42mm
•   1x Variator Shaft Thread: M12
•   1x Variator Shaft Splines: 26
•   1x Variator Shaft Bearing: 47mm
•   1x Made in Taiwan
   Fit Flywheel Shaft Nut: M10 / Washer: M10 Socket: 14mm
   Fit Variator Shaft Nut: M12 / Washer: M12 / Socket: 17mm
•   Fit Oil Pump Sprocket: 33T
•   Fit Timing Cover: 33T
•   Fit Oil Pump Sprocket: 33T
•   Fit Dowel Pin Set (
•   Fit Dowel Pin Set (10x20mm)
•   Fit QMB 49/50cc+

Supported Models: 139QMB 49cc-50cc engines, Baja SC50, Boreem (BMS) 50, Filly 50, Kymco 50, Panterra 50, Qingqi 50, QLink 50, Roketa 50, SUNL 50, SYM 50, Tank 50, TaoTao 50, and virtually any other scooter engine with these measurements.

Item Weight & Product Dimensions:
•    3.837 pounds | 9.724” (L) x 6.027” (W) x 3.353” (H)

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101-Octane Crankshaft 41.4mm 16T Stroker (139QMB)
  • Stock: 39
  • Reward Points: 2
  • Part #: BT7001-16
Sold: 5
Views: 14240
Ex Tax: $73.59
Price in reward points: 74