Cvk Main Jet (# 127) for Scooters & Mopeds

Main Jet #127 for 139QMB and GY6 Scooters

The #127 main jet suits 139QMB and GY6 scooters and mopeds, and it will work with nearly any CVK carburetor that has a 5mm main jet slot. It plays a central role in controlling fuel flow to the engine, so it affects how your vehicle runs. You can find it alongside other scooter carburetors & jets that may help with performance. Expect to experiment a little to get the best result, and refer to jetting instructions for direction.

Build and Specifications

This jet uses a Keihin round design, so it fits a range of scooter models. It has an M5x0.80 thread and measures 8mm overall in length. It is manufactured to firm quality standards, which makes it a dependable pick for scooter owners.

Fitting and Tuning

To fit it, take out the current jet and screw in this replacement. A snug, correct seating matters for smooth engine operation. You may need to make small adjustments to reach the fuel mixture you want, something riders commonly do when fine-tuning an engine.

Specifications

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

Fitment

Compatible with:

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

How to choose: Pick a CVK carburetor with a 5mm main jet slot, and confirm the jet has an M5x0.80 thread and 8mm overall length. Tuning takes some trial and error.

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