Cvk Main Jet (# 148) for Scooters & Mopeds

Cvk Main Jet (#148) for 139QMB and GY6 Engines

This Cvk Main Jet (#148) suits scooters and mopeds running 139QMB or GY6 engines. It works with a range of CVK carburetors that have a 5mm main jet slot. Because it controls how much fuel reaches the engine, it plays a big role in overall performance. You can find it among the scooter carburetors & jets used to fine-tune throttle response and fuel economy.

Build and Specifications

The jet uses a Keihin round design, which gives it a secure fit and dependable operation. It has an M5x0.80 thread and measures 8mm overall. Its precise dimensions allow for fine jetting changes, though dialing in the right setting often takes some testing.

Signs You Should Swap the Main Jet

Consider replacing the main jet if the scooter accelerates poorly, cuts out, or runs unevenly. After altering the engine or carburetor, you may need to retune with a different jet to restore good running.

Specifications

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

Fitment

Fits:

• 139QMB-based 50cc/80cc engines (engine codes 139QMA, 139QMB, 1P39QMB, 1P39QMA-2, YN139QMB, JJ1P39QMB, 139FMA-2, BD1P39QMB, BN139QMB, 147QMD, other QMA and QMB models)
• 157QMJ-based 125cc/150cc/169cc engines (engine codes 157QMJ, 161QMK, 152QMI, 1P61QMK, YN1P57QMJ, 1P52FMI, 154FMI, JJ157QMJ, 1P57QMJ, BN157QMJ, BN161QMK-A, other QMJ, QMK and QMI models)
• Any engine code with QM or FM and a 5mm main jet slot CVK carburetor

How to choose: Confirm that your CVK carburetor has a 5mm main jet slot and an M5x0.80 thread, then select the jet size your engine calls for. Finding the best size usually involves some trial and error.

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