GY6 50cc Crankshaft | 50cc & 80cc Scooter, 16 or 22 Teeth

GY6 50cc Crankshaft for 50cc & 80cc Scooter Engines – 16 or 22 Teeth, 45# Steel

Dhs. 279.32

GY6 50cc Crankshaft for 50cc and 80cc Scooter Engines

This GY6 50cc crankshaft is a replacement crankshaft and connecting rod assembly for GY6-type 50cc and 80cc scooter engines. It is made from 45# medium carbon steel and comes in two versions, with a 16-tooth or a 22-tooth oil pump drive gear, so you can match the gear on your original crankshaft. Easy Life Markets sells it for scooter owners and repair shops rebuilding the bottom end of these small four-stroke engines.

The GY6 design is one of the most widely used small scooter engines, found in many brands of 50cc scooters and mopeds. The 50cc version (often called 139QMB) and the 80cc big bore version share the same basic crankcase, which is why a single crankshaft is listed for both. A worn crankshaft or connecting rod bearing is a common reason for noise and vibration on older, high-mileage scooters.

Choose Your Version: 16 Teeth or 22 Teeth

The oil pump on GY6 50cc engines is driven from the crankshaft, and two different drive gear sizes were used: 16 teeth and 22 teeth. The two versions are not interchangeable, because the gear must match the rest of your oil pump drive.

16 Teeth: choose this if your original crankshaft has a 16-tooth oil pump gear.
22 Teeth: choose this if your original crankshaft has a 22-tooth oil pump gear.

Count the teeth on your old crankshaft's gear before ordering. The product photos include a picture that shows the gear versions.

What Is Included

1 x crankshaft with connecting rod, in the gear version you select

Main bearings, oil seals, cam chain and gaskets are not listed as included.

Specifications

Product type: Scooter engine crankshaft and connecting rod assembly
Listed engines: GY6 50cc and 80cc
Material: 45# medium carbon steel
Versions: 16-tooth or 22-tooth oil pump gear
Quantity: 1 crankshaft
SKU: CJYD232049301AZ (16 teeth), CJYD232049302BY (22 teeth)

The material grade is a common engineering steel. You can read more about carbon steel and why medium carbon grades are used for shafts and gears.

Checking Fitment

Not every 50cc scooter uses a GY6 engine. Many use a two-stroke engine or a different four-stroke design. Before ordering:

Confirm your engine is a GY6 50cc or 80cc four-stroke, usually marked 139QMB or similar on the crankcase.
Count the oil pump gear teeth on your old crankshaft (16 or 22).
Compare the crankshaft with our photos: shaft lengths on both sides, splines, threads and the cam chain sprocket.

If anything looks different, send us photos of your old crankshaft before ordering.

Signs Your Crankshaft Needs Replacing

Knocking or rattling from the bottom end
Strong vibration that gets worse with speed
Play in the connecting rod big end when checked by hand
Damaged splines, keyway or threads on the variator or magneto side
Oil seal leaks that keep coming back because the shaft runs out of true

Rebuild Tips

Replacing the crankshaft means splitting the crankcase, so plan it as a full bottom-end rebuild.
Fit new main bearings and crankshaft oil seals at the same time.
Check the cam chain and tensioner, and the oil pump and its drive, while the engine is open.
Clean the crankcase halves thoroughly and use a new crankcase gasket.
Line up the timing marks on the cam sprocket and crankshaft when reassembling the top end.

After the Rebuild

Run the engine gently for the first few hundred kilometers, change the oil early to flush out assembly debris, and then keep to regular oil changes. Small scooter engines hold very little oil, so checking the level often helps protect the new crankshaft.

How the GY6 50cc Bottom End Works

In a GY6 50cc engine, the crankshaft sits in two main bearings in the crankcase. One end carries the magneto rotor and the cam chain sprocket, and the other end drives the variator of the automatic CVT transmission. The oil pump is driven by a gear on the crankshaft, which is why the tooth count matters. Because the variator end carries so much load, a worn crankshaft often shows up first as a noisy or wobbling variator, or as a leaking oil seal on that side.

When you strip the engine, check the crankshaft runout, the big-end play and the condition of the variator splines. If any of these are out of limits, fitting a new crankshaft assembly is the most reliable repair and saves you from rebuilding the engine twice.

Who This Crankshaft Is For

This crankshaft suits scooter repair shops, riders who maintain their own GY6 50cc or 80cc scooter, and anyone reviving a noisy or seized small four-stroke engine.

Common Questions

Will it fit a GY6 125cc or 150cc engine? No. The 125cc and 150cc GY6 engines use a different, larger crankshaft.

Which gear version do I need? Count the teeth on the oil pump gear of your old crankshaft, and choose 16 or 22 teeth to match.

Buy the GY6 50cc Crankshaft at Easy Life Markets

You can order this crankshaft right here. Select the 16-tooth or 22-tooth version above. The current price and availability are shown on this page. Please read our return and refund policy before buying.