Cvk Main Jet (# 125) for Scooters & Mopeds

#125 Main Jet for 139QMB and GY6 Scooters

The #125 main jet suits 139QMB and GY6 engines and works with a range of CVK carburetors that have a 5mm main jet slot. It controls how much fuel reaches the engine, so it has a real effect on how smoothly and efficiently your scooter runs. You can find more options in our range of carburetors and jets for scooters, which can help you get more from your ride.

Compatibility and Usage

This jet works with 50cc and 80cc engines built on the 139QMB platform, along with 125cc, 150cc, and 169cc engines based on the 157QMJ series. Getting the jetting right often takes some trial and adjustment. For fine-tuning, it's worth reading a jetting guide before you make changes.

Specifications

• Thread Size: M5x0.80
• Overall Length: 8mm
• Type: Keihin round-style main jet
• Fits: 139QMB-based 50cc/80cc GY6 engines and 157QMJ-based 125cc/150cc/169cc engines with 5mm main jet slot CVK

Fitment

Fits:

• 139QMA, 139QMB, 1P39QMB, 1P39QMA-2, YN139QMB, JJ1P39QMB, 139FMA-2, BD1P39QMB, BN139QMB, 147QMD engines (50cc/80cc)
• 157QMJ, 161QMK, 152QMI, 1P61QMK, YN1P57QMJ, 1P52FMI, 154FMI, JJ157QMJ, 1P57QMJ, BN157QMJ, BN161QMK-A engines (125cc/150cc/169cc)
• Other QMA and QMB engines (50cc/80cc)
• Other QMJ, QMK and QMI engines (125cc/150cc/169cc)

How to choose: Check that the 5mm main jet slot on your CVK carburetor matches, and confirm the engine code (QM or FM) printed on your engine. Expect some trial and error when setting the jetting.

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